Ophthalmic device and ophthalmic optical system

ABSTRACT

An ophthalmic device for observing a subject eye, including: a light source; a scanning section that scans light from the light source; and an objective optical system configured to form a pupil, which has a conjugate relationship with a pupil of the subject eye, at the scanning section, wherein the objective optical system has, in order from the scanning section toward the subject eye, a first lens group that is positive, a second lens group that is positive, and a third lens group that is disposed between the first lens group and the second lens group, and that includes a concave surface configured to diverge light.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation application of InternationalApplication No. PCT/JP2020/035561, filed Sep. 18, 2020, the disclosureof which is incorporated herein by reference in its entirety. Further,this application claims priority from Japanese Patent Application No.2019-179050, filed Sep. 30, 2019, the disclosure of which isincorporated herein by reference in its entirety.

TECHNICAL FIELD

The present invention relates to an ophthalmic device and an ophthalmicoptical system.

BACKGROUND ART

European Patent Application Publication No. EP 2901919 A1 discloses anophthalmic device having an attachment lens for capturing an image of afundus that has a wide field angle.

SUMMARY

A first aspect of the technique of the present disclosure is anophthalmic device for observing a subject eye, including: a lightsource; a scanning section that scans light from the light source; andan objective optical system configured to form a pupil, which has aconjugate relationship with a pupil of the subject eye, at the scanningsection, wherein the objective optical system has, in order from thescanning section toward the subject eye, a first lens group that ispositive, a second lens group that is positive, and a third lens groupthat is disposed between the first lens group and the second lens group,and that includes a concave surface configured to diverge light.

A second aspect of the technique of the present disclosure is anophthalmic optical system for observing a subject eye, including anobjective optical system configured to forms a pupil having a conjugaterelationship with a pupil of the subject eye, wherein the objectiveoptical system has, in order from a side at which the pupil having aconjugate relationship with the pupil of the subject eye is formed,toward the subject eye, a first lens group that is positive, a secondlens group that is positive, and a third lens group that includes aconcave surface configured to diverge light and that is disposed betweenthe first lens group and the second lens group.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a structural drawing of an ophthalmic device of a firstembodiment.

FIG. 2 is a schematic structural drawing of an imaging optical system ofthe first embodiment.

FIG. 3 is a structural drawing of an objective lens that structures theimaging optical system.

FIG. 4 is a structural drawing illustrating an example of the lensstructure of an objective lens relating to Example 1.

FIG. 5 is an aberration graph illustrating lateral aberration of theobjective lens relating to Example 1.

FIG. 6 is a structural drawing illustrating an example of the lensstructure of an objective lens relating to Example 2.

FIG. 7 is an aberration graph illustrating lateral aberration of theobjective lens relating to Example 2.

FIG. 8 is a structural drawing illustrating an example of the lensstructure of an objective lens relating to Example 3.

FIG. 9 is an aberration graph illustrating lateral aberration of theobjective lens relating to Example 3.

FIG. 10 is a structural drawing illustrating an example of the lensstructure of an objective lens relating to Example 4.

FIG. 11 is an aberration graph illustrating lateral aberration of theobjective lens relating to Example 4.

FIG. 12 is a schematic structural drawing illustrating a structure inwhich an attached optical system relating to a second embodiment is madeto be attachable to and removable from a portable terminal.

FIG. 13 is a schematic structural drawing illustrating an example of thestructure of the attached optical system relating to the secondembodiment.

FIG. 14 is a schematic structure drawing of an objective lens thatstructures an imaging optical system of a third embodiment.

FIG. 15 is a structural drawing illustrating an example of the lensstructure of an objective lens relating to Example 5.

FIG. 16 is a schematic structure drawing of an objective lens thatstructures an imaging optical system of a fourth embodiment.

FIG. 17 is a schematic structural drawing of an ophthalmic device of asixth embodiment.

FIG. 18 is a schematic structural drawing of an imaging optical systemrelating to a first structural example of a seventh embodiment.

FIG. 19 is a schematic structural drawing of an imaging optical systemrelating to a second structural example of the seventh embodiment.

FIG. 20 is a schematic structural drawing of an imaging optical systemrelating to a third structural example of the seventh embodiment.

FIG. 21 is a schematic structural drawing of an imaging optical systemrelating to a fourth structural example of the seventh embodiment.

FIG. 22 is a schematic structural drawing of an imaging optical systemrelating to a fifth structural example of the seventh embodiment.

FIG. 23 is a schematic structural drawing of an imaging optical systemrelating to a sixth structural example of the seventh embodiment.

FIG. 24 is a schematic structural drawing of an imaging optical systemrelating to a seventh structural example of the seventh embodiment.

DESCRIPTION OF EMBODIMENTS

Embodiments of the present disclosure are described in detailhereinafter with reference to the drawings.

First Embodiment

An ophthalmic device 110 relating to a first embodiment of the presentdisclosure is described hereinafter with reference to the drawings.

The schematic structure of the ophthalmic device 110 is illustrated inFIG. 1.

For convenience of explanation, a scanning laser ophthalmoscope iscalled “SLO”. Further, optical coherence tomography is called “OCT”.

Note that the horizontal direction, in a case in which the ophthalmicdevice 110 is set on a horizontal surface, is the “X direction”, thedirection orthogonal to the horizontal surface is the “Y direction”, andthe optical axis direction of an imaging optical system 116A is the “Zdirection”. The device is placed, with respect to an subject eye, suchthat the center of pupil d of the subject eye is positioned on theoptical axis that is the Z direction. Further, the X direction, the Ydirection and the Z direction are orthogonal to one another.

The ophthalmic device 110 includes an imaging device 14 and a controldevice 16. The imaging device 14 has a SLO unit 18 that acquires animage of the fundus of an subject eye 12, and an OCT unit 20 thatacquires a tomographic image of the subject eye 12. Hereinafter, thefundus image that is generated on the basis of the SLO data acquired bythe SLO unit 18 is called a SLO image. Further, the tomographic imagethat is generated on the basis of the OCT data acquired by the OCT unit20 is called an OCT image. Note that the SLO image is also referred toas a two-dimensional fundus image. Further, the OCT image is alsoreferred to as a fundus tomographic image and an anterior eye portiontomographic image, in accordance with the imaged region of the subjecteye 12.

The ophthalmic device 110 is an example of the “ophthalmic device” ofthe technique of the present disclosure.

The control device 16 has a computer having a CPU (Central ProcessingUnit) 16A, a RAM (Random Access Memory) 16B, a ROM (Read Only Memory)16C, and an input/output port (I/O) 16D.

The control device 16 has an input/display device 16E that is connectedto the CPU 16A via the I/O port 16D. The input/display device 16E has agraphic user interface that displays the image of the subject eye 12 andreceives various instructions from the user. A touch panel display canbe used as the input/display device 16E. The control device 16 also hasa communication I/F 16F that is connected to the I/O port 16D.

Further, the control device 16 has an image processing device 17 that isconnected to the I/O port 16D. The image processing device 17 generatesan image of the subject eye 12 on the basis of data obtained by theimaging device 14.

As described above, in FIG. 1, the control device 16 of the ophthalmicdevice 110 has the input/display device 16E, but the technique of thepresent disclosure is not limited to this. For example, the controldevice 16 of the ophthalmic device 110 may not have the input/displaydevice 16E, and may have a separate input/display device that isphysically independent of the ophthalmic device 110. In this case, thedisplay device has an image processing processor unit that operatesunder the control of the CPU 16A of the control device 16. The imageprocessing processor unit may display the SLO image and the like on thebasis of image signals that are outputted and instructed from the CPU16A.

The imaging device 14 operates under the control of the control device16. The imaging device 14 includes the SLO unit 18, the imaging opticalsystem 116A and the OCT unit 20. The imaging optical system 116A ismoved in the X, Y, Z directions by an imaging optical system drivingsection (not illustrated), under the control of the CPU 16A. Thealigning (positioning) of the imaging device 14 and the subject eye 12may be carried out, for example, by moving not merely the imaging device14, but the entire ophthalmic device 110 in the X, Y, Z directions.

A SLO system is realized by the control device 16, the SLO unit 18 andthe imaging optical system 116A that are illustrated in FIG. 1.

The SLO unit 18 has plural light sources. For example, as illustrated inFIG. 1, the SLO unit 18 has a light source 40 of B light (blue colorlight), a light source 42 of G light (green color light), a light source44 of R light (red color light), and a light source 46 of IR light(infrared light (e.g., near infrared light)). The lights that exit fromthe respective light sources 40, 42, 44, 46 are directed toward the sameoptical path via respective optical members 48, 50, 52, 54, 56. Theoptical members 48, 56 are mirrors, and the optical members 50, 52, 54are beam splitters. The B light is guided via the optical members 48,50, 54 to the optical path of the imaging optical system 116A. The Glight is guided via the optical members 50, 54 to the optical path ofthe imaging optical system 116A. The R light is guided via the opticalmembers 52, 54 to the optical path of the imaging optical system 116A.The IR light is guided via the optical members 56, 52 to the opticalpath of the imaging optical system 116A. Note that LED light sources orlaser light sources can be used as the light sources 40, 42, 44, 46.Note that an example using laser light sources is described hereinafter.Total reflection mirrors can be used as the optical members 48, 56.Further, dichroic mirrors, half mirrors or the like can be used as theoptical members 50, 52, 54.

The light sources 40, 42, 44, 46 are examples of the “light source” ofthe technique of the present disclosure.

The SLO unit 18 is structured so as to be able to be switched betweenvarious light-emitting modes such as a light-emitting mode in which Glight, R light, B light and IR light are respectively emittedindependently, a light-emitting mode in which these lights are allemitted simultaneously or some thereof are emitted simultaneously, andthe like. In the example illustrated in FIG. 1, the four light sourcesthat are the light source 40 of B light (blue color light), the lightsource 42 of G light, the light source 44 of R light, and the lightsource 46 of IR light are provided, but the technique of the presentdisclosure is not limited to this. For example, the SLO unit 18 mayfurther have a light source of white light. In this case, in addition tothe above-described various light-emitting modes, a light-emitting modein which only white light is emitted, or the like, may be set.

The laser light that is incident on the imaging optical system 116A fromthe SLO unit 18 is scanned in the X direction and the Y direction byscanning sections (120, 142) that are described later. The scanninglight is illuminated, via pupil 27, onto the posterior eye portion(e.g., the fundus) of the subject eye 12. The reflected light that isreflected by the fundus is incident, via the imaging optical system116A, onto the SLO unit 18.

The scanning sections (120, 142) are examples of the “scanning sections”of the technique of the present disclosure.

The reflected light that is reflected at the fundus of the subject eye12 is detected by light detecting elements 70, 72, 74, 76 that areprovided at the SLO unit 18. In the present embodiment, the SLO unit 18has the B light detecting element 70, the G light detecting element 72,the R light detecting element 74 and the IR light detecting element 76,in correspondence with the plural light sources, i.e., the B lightsource 40, the G light source 42, the R light source 44 and the IR lightsource 46. The B light detecting element 70 detects the B light that isreflected at the beam splitter 64. The G light detecting element 72detects the G light that is transmitted through the beam splitter 64 andreflected at the beam splitter 58. The R light detecting element 74detects the R light that is transmitted through the beam splitters 64,58 and is reflected at the beam splitter 60. The IR light detectingelement 76 detects the G light that is transmitted through the beamsplitters 64, 58, 60 and is reflected at the beam splitter 62. APDs(avalanche photodiodes) are examples of the light detecting elements 70,72, 74, 76.

Under the control of the CPU 16A, the image processing device 17generates SLO images corresponding to the respective colors, by usingthe signals detected by the B light detecting element 70, the G lightdetecting element 72, the R light detecting element 74 and the IR lightdetecting element 76, respectively. The SLO images corresponding to therespective colors are a B-SLO image generated by using the signalsdetected by the B light detecting element 70, a G-SLO image generated byusing the signals detected by the G light detecting element 72, an R-SLOimage generated by using the signals detected by the R light detectingelement 74, and an IR-SLO image generated by using the signals detectedby the IR light detecting element 76. Further, in the case of thelight-emitting mode in which the B light source 40, the G light source42 and the R light source 44 emit light simultaneously, an RGB-SLO imagemay be synthesized from the B-SLO image, the G-SLO image and the R-SLOimage that are generated by using the respective signals detected by theR light detecting element 74, the G light detecting element 72 and the Blight detecting element 70. Further, in the case of the light-emittingmode in which the G light source 42 and the R light source 44 emit lightsimultaneously, an RG-SLO image may be synthesized from the G-SLO imageand the R-SLO image that are generated by using the respective signalsdetected by the R light detecting element 74 and the G light detectingelement 72. Although an RG-SLO image is used as the SLO image in thefirst embodiment, the technique of the present disclosure is not limitedto this, and another SLO image can be used.

Dichroic mirrors, half mirrors or the like can be used for the beamsplitters 58, 60, 62, 64.

The OCT system is a three-dimensional image acquiring device that isrealized by the control device 16, the OCT unit 20 and the imagingoptical system 116A that are illustrated in FIG. 1. The OCT unit 20includes a light source 20A, a sensor (detecting element) 20B, a firstoptical coupler 20C, a reference optical system 20D, a collimator lens20E and a second optical coupler 20F.

The light source 20A emits light for optical coherence tomography. Forexample, a super luminescent diode (SLD) can be used as the light source20A. The light source 20A generates low interference light of abroadband light source that has a wide spectral width. The light thatexits from the light source 20A is split at the first optical coupler20C. One divisional light is made into parallel light at the collimatorlens 20E as measurement light, and thereafter, is made incident on theimaging optical system 116A. The measurement light is scanned in the Xdirection and the Y direction by scanning sections (148, 142) that aredescribed later. The scanning light is illuminated onto the anterior eyeportion of the subject eye, or onto the posterior eye portion via thepupil 27. The measurement light that is reflected by the anterior eyeportion or the posterior eye portion goes through the imaging opticalsystem 116A and is made incident on the OCT unit 20, and, via thecollimator lens 20E and the first optical coupler 20C, is incident onthe second optical coupler 20F. Note that, in the present embodiment, anSD-OCT using an SLD is given as an example of the light source 20A, butthe technique of the present disclosure is not limited to this, and anSS-OCT that uses a wavelength sweeping light source may be employedinstead of an SLD.

The other light, which exits from the light source 20A and isbranched-off at the first optical coupler 20C, is incident on thereference optical system 20D as reference light, and goes through thereference optical system 20D and is incident on the second opticalcoupler 20F.

The measurement light (returned light) that is reflected and scatteredat the subject eye 12, and the reference light, are combined at thesecond optical coupler 20F, and interference light is generated. Theinterference light is detected at the sensor 20B. On the basis of adetection signal (OCT data) from the sensor 20B, the image processingdevice 17 generates a tomographic image of the subject eye 12.

In the first embodiment, the OCT system generates a tomographic image ofthe anterior eye portion or the posterior eye portion of the subject eye12.

The anterior eye portion of the subject eye 12 is the portion thatincludes, for example, the cornea, the iris, the corner angle, the lens,the ciliary body and a portion of the vitreous body, as the anterior eyesegment. The posterior eye portion of the subject eye 12 is the portionthat includes, for example, the remaining portion of the vitreous body,the retina, the choroid and the sclera, as the posterior eye segment.Note that the vitreous body that belongs to the anterior eye portion isthe portion of the vitreous body that is at the cornea side, with theborder being the X-Y plane that passes through the point of the lensthat is nearest to the center of the eyeball. The vitreous body thatbelongs to the posterior eye portion is the portion of the vitreous bodythat is other than the vitreous body belonging to the anterior eyeportion.

In a case in which the anterior eye portion of the subject eye 12 is theregion that is the object of imaging, the OCT system generates atomographic image of the cornea for example. Further, in a case in whichthe posterior eye portion of the subject eye 12 is the region that isthe object of imaging, the OCT system generates a tomographic image ofthe retina for example.

The schematic structure of the imaging optical system 116A isillustrated in FIG. 2. The imaging optical system 116A has an objectivelens 130, the horizontal scanning section 142, a relay lens device 140,a beam splitter 147, the vertical scanning sections 120, 148, a focusadjusting device 150 and the collimator lens 20E that are disposed inthat order from the subject eye 12 side.

For example, dichroic mirrors, half mirrors or the like can be used asbeam splitters 178, 147.

The horizontal scanning section 142 is an optical scanner that scans, inthe horizontal direction, the laser light of SLO and the measurementlight of OCT that are incident via the relay lens device 140. In thepresent embodiment, the horizontal scanning section 142 is shared by theSLO optical system and the OCT optical system, but the technique of thepresent disclosure is not limited to this. A horizontal scanning sectionmay be provided for each of the SLO optical system and the OCT opticalsystem.

The collimator lens 20E makes, into parallel light, the measurementlight that exits from end portion 158 of a fiber through which the lightexiting from the OCT unit 20 advances.

The focus adjusting device 150 has plural lenses 152, 154. The focusadjusting device 150 adjusts the focus position of the measurement lightat the subject eye 12 by moving the plural lenses 152, 154 respectivelyin the optical axis direction appropriately in accordance with theregion to be imaged at the subject eye 12. Note that, although notillustrated, in a case in which a focus detecting device is provided, anautofocus device can be realized by driving the lenses 152, 154 by thefocus adjusting device in accordance with the state of focal pointdetection, and carrying out focusing automatically.

The vertical scanning section 148 is an optical scanner that scans, inthe vertical direction, the measurement light that is incident thereonvia the focus adjusting device 150.

The vertical scanning section 120 is an optical scanner that scans, inthe vertical direction, the laser light that is incident thereon fromthe SLO unit 18.

The relay lens device 140 has plural lenses 144, 146 that have positivepower. The relay lens device 140 is structured by the plural lenses 144,146 such that the positions of the vertical scanning sections 148, 120and the position of the horizontal scanning section 142 are conjugate.More specifically, the relay lens device 140 is structured such that thecentral positions of the angular scanning of the both scanning sectionsare conjugate.

The beam splitter 147 is disposed between the relay lens device 140 andthe vertical scanning section 148. The beam splitter 147 is an opticalmember that combines the SLO optical system and the OCT optical system,and reflects the SLO light, which exits from the SLO unit 18, toward therelay lens device 140, and transmits the measurement light, which exitsfrom the OCT unit 20, toward the relay lens device 140. The measurementlight that exits from the OCT unit 20 is two-dimensionally scanned bythe vertical scanning section 148 and the horizontal scanning section142. Further, the light that exits from the SLO unit 18 istwo-dimensionally scanned by the vertical scanning section 120 and thehorizontal scanning section 142 that structure the SLO optical system.The OCT measurement light and the SLO laser light that are scannedtwo-dimensionally are respectively made incident onto the subject eye 12via the objective lens 130 that structures a shared optical system. TheSLO laser light that is reflected at the subject eye 12 goes through theobjective lens 130, the horizontal scanning section 142, the relay lensdevice 140, the beam splitter 147 and the vertical scanning section 120,and is made incident on the SLO unit 18. Further, the OCT measurementlight that has gone through the subject eye 12 goes through theobjective lens 130, the horizontal scanning section 142, the relay lensdevice 140, the beam splitter 147, the vertical scanning section 148,the focus adjusting device 150 and the collimator lens 20E, and is madeincident on the OCT unit 20.

For example, resonant scanners, galvano mirrors, polygon mirrors,rotating mirrors, dove prisms, double dove prisms, rotation prisms, MEMSmirror scanners, acousto-optic elements (AOMs) and the like are suitablyused as the horizontal scanning section 142 and the vertical scanningsections 120, 148. In the present embodiment, a galvano mirror is usedas the vertical scanning section 148, and further, a polygon mirror isused as the vertical scanning section 120. Note that, in a case in whicha two-dimensional optical scanner such as a MEMS mirror scanner or thelike is used instead of an optical scanner such as a polygon mirror or agalvano mirror or the like, the incident light can be angle-scannedtwo-dimensionally by that reflecting element, and therefore, the relaylens device 140 may be eliminated.

The objective lens 130 has, in order from the horizontal scanningsection 142 side, a first lens group 134 and a second lens group 132. Atleast the second lens group 132 is, overall, a positive lens grouphaving positive power. In the first embodiment, the first lens group 134as well is, overall, a positive lens group having positive power. Eachof the first lens group 134 and the second lens group 132 has at leastone positive lens. In a case in which each of the first lens group 134and the second lens group 132 has plural lenses, the first lens group134 and the second lens group 132 may include a negative lens, providedthat each of the first lens group 134 and the second lens group 132 haspositive power overall.

Further, the objective lens 130 of the present disclosure has a thirdlens group 133 in the space between the first lens group 134 and thesecond lens group 132.

The first lens group 134 is an example of the “first lens group” of thetechnique of the present disclosure, the second lens group 132 is anexample of the “second lens group” of the technique of the presentdisclosure, and the third lens group 133 is an example of the “thirdlens group” of the technique of the present disclosure.

The first lens group 134 and the second lens group 132 that structurethe objective lens 130 are separated by the longest air gap on opticalaxis AX between lens surfaces at the objective lens 130. The third lensgroup 133 is disposed in the space of this longest air gap.

As a result, the gap between the first lens group 134 and the third lensgroup 133, and the air gap between the third lens group 133 and thesecond lens group 132, are the largest air gap and the second largestair gap among the lens gaps of the entire objective lens 130. In a casein which the third lens group 133 that is the intermediate group isdisposed at the subject eye 12 side between the first lens group 134 andthe second lens group 132, the gap between the first lens group 134 andthe third lens group 133 is the largest. In a case in which the thirdlens group 133 is disposed at the scanning section side, the gap betweenthe third lens group 133 and the second lens group 132 is the largest.Note that, even if there is a glass plate that does not have power at aposition between the first lens group 134 and the second lens group 132,the glass plate is not considered to be a lens that belongs to eitherthe first lens group 134 or the second lens group 132, and it isconsidered that the first lens group 134 and the second lens group 132are separated by the longest air gap. This longest air gap is convenientfor providing a combining section that has light combining and lightsplitting functions such as a dichroic mirror or the like.

Note that, although not illustrated, the imaging optical system 116A canhave an optical module that includes a fixation lamp that provides afixation target, a camera and an illumination device. Such an opticalmodule can be disposed so as to be combined into the optical path of theimaging optical system 116A by a beam splitter or the like.

The imaging optical system 116A has the objective lens 130 thatfunctions as a posterior eye portion observing optical system thatobserves the posterior eye portion that includes at least the fundus ofthe subject eye 12. Due to the imaging optical system 116A having anoptical module (not illustrated) for anterior eye portion observationthat can be inserted onto and removed from the optical path of theobjective lens 130, and the optical module for anterior eye portionobservation being placed on the optical path of the objective lens 130,the imaging optical system 116A can be switched from the posterior eyeportion observing optical system to the anterior eye portion observingoptical system. In the first embodiment, the imaging optical system 116Ais described with the focus being on the posterior eye portion observingoptical system, and description of the imaging optical system 116A,which functions as an anterior eye portion observing optical system inwhich an optical module for anterior eye portion observation is placedon the optical path of the objective lens 130, is omitted.

An example of the concrete structure of the objective lens 130, whichstructures the imaging optical system 116A that functions as a posterioreye portion observing optical system that observes the posterior eyeportion of the subject eye 12, is illustrated in FIG. 3.

The scanning center positions of the horizontal scanning section 142 andthe vertical scanning section 148 illustrated in FIG. 2 correspond toscanning center position Ps that is illustrated in FIG. 3. The objectivelens 130 is disposed such that this scanning center position Ps isconjugate with pupil position P2 of the subject eye 12. Namely, this isa structure in which the scanning center position Ps of the scanningsections coincides with the pupil position (hereinafter called pupilconjugate position P1) that has a conjugate relationship with the pupilposition P2 of the subject eye 12. In a SLO optical system, the SLOlaser light that is scanned by the vertical scanning section 120 and thehorizontal scanning section 142 goes through the objective lens 130 andis angle-scanned two-dimensionally with the pupil position P2 of thesubject eye 12 being the center. As a result, the collected point of theSLO laser light is scanned two-dimensionally at the fundus of thesubject eye 12. Further, at the OCT optical system as well, similarly,the measurement light that is scanned by the vertical scanning section148 and the horizontal scanning section 142 goes through the objectivelens 130 and is angle-scanned two-dimensionally with the pupil positionP2 of the subject eye 12 being the center. As a result, the collectedpoint of the measurement light is scanned two-dimensionally at thefundus of the subject eye 12. In a case of observing the posterior eyeportion, a fundus two-dimensional image is acquired by the SLO unit 18,and a fundus tomographic image is acquired by the OCT unit 20.

The important point in such a structure is that the light that issupplied to the respective SLO and OCT scanning sections is a parallellight bundle, and the parallel light bundle is angle-scanned at thepupil P2 of the subject eye by the angular scanning by the scanningsection. Therefore, the objective lens 130 must structure an afocalsystem on the whole. Further, the scanning angle of the parallel lightbundle at the pupil P2 of the subject eye is determined by the scanningangles at the scanning sections and the angular magnification of theobjective lens 130. In this case, for paraxial angular magnification Mof the objective lens 130, a range of around 1.5× to 5× (1.5 □ M □ 5) ispreferable.

An intermediate pupil position P3 is formed in the third lens group 133(G3) that serves as an intermediate group. The light beams illustratedin FIG. 3 are the respective main light beams of scanning light bundlesof five angles up to the maximum angle that are incident on the pupil P2of the subject eye 12, and this is clear from the fact that these mainlight beams intersect in the third lens group 133 (G3).

Specifically, the objective lens 130 functions as an optical system thattransfers the scanning center position Ps of the scanning section to thepupil (the pupil position P2) of the subject eye 12, and has plural lensgroups including the first lens group 134 (G1) that is positive and thesecond lens group 132 (G2) that is positive. The objective lens 130 isstructured such that the position (hereinafter called the intermediatepupil position P3), which is in a conjugate relationship with thescanning center position Ps of the scanning section, is formed betweenthe first lens group 134 and the second lens group 132. Namely, thescanning center position Ps is the pupil conjugate position P1, and isconjugate with the pupil position P2 of the subject eye 12 and theintermediate pupil position P3, and the first lens group 134 is apositive lens group, and the second lens group 132 also is a positivelens group. In the example illustrated in FIG. 3, the first lens group(G1) includes, in order from the pupil conjugate position P1 side thatis the scanning section side (e.g., the nearest horizontal scanningsection 142 side) toward the subject eye 12 side, a positive meniscuslens L11 whose convex surface faces the scanning section side, anegative lens L12 whose concave surface faces the scanning section side,a positive meniscus lens L13 whose concave surface faces the scanningsection side, and a lens component (a cemented lens of negative lens L14and positive lens L15) that is positive at the scanning section side.Note that “lens component” in the present specification means a lens inwhich there are two interfaces that contact air on the optical axis. Onelens component means one single lens, or one cemented lens that isstructured by plural lenses being cemented together. A case in which thelens component of the first lens group 134 is a cemented lens asillustrated is effective for chromatic aberration correction, but thelens component of the first lens group 134 can be made to be a singlelens in a case in which the wavelength region of the lights that areused is relatively narrow.

The second lens group 132 (G2) includes, in order from the scanningsection side toward the subject eye side, a positive lens L21, a lenscomponent (a cemented lens of a positive lens L22 and a negative lensL23) that is shaped as a positive meniscus whose convex surface facesthe scanning section side, and a positive meniscus lens L24 whose convexsurface faces the scanning section side. A case in which themeniscus-shaped lens component of the second lens group 132 is acemented lens as illustrated is effective for chromatic aberrationcorrection, but the lens component of the second lens group 132 can bemade to be a single lens in a case in which the wavelength region of thelights that are used is relatively narrow.

The third lens group 132 (G3) includes, in order from the scanningsection side toward the subject eye side, a lens component (e.g., acemented lens of a positive lens L31 and a negative lens L32) that ispositive or negative at the scanning section side, a meniscus lens L33whose convex surface faces the scanning section side, and a meniscuslens L34 whose concave surface faces the scanning section side. Thethird lens group 133 is formed so as to include the intermediate pupilposition P3. It is preferable for there to be a structure in which theconjugate point P3 of the pupil is formed between the negative meniscuslens L33 whose convex surface faces the scanning section side and themeniscus negative lens L34 whose concave surface faces the scanningsection side, i.e., at a position sandwiched between the concavesurfaces of the both lenses.

Note that the first lens group 134 (G1) and the second lens group 132(G2) both have positive refractive powers, but it suffices for the thirdlens group 133 (G3) that serves as an intermediate group to have astrong diverging surface in the vicinity of the intermediate pupilposition that is extremely effectively in correcting aberration.Although it is preferable for the refractive power of the third lensgroup 133 (G3) to mainly be positive, the refractive power can also benegative.

Here, due to the imaging optical system 116A forming a wide angleoptical system, observation at a wide field of view FOV at the fundus ofthe subject eye 12 is realized. The field of view FOV means the rangethat can be imaged by the imaging device 14. The field of view FOV canbe expressed as the viewing angle. In the first embodiment, the viewingangle can be prescribed by the internal illumination angle and theexternal illumination angle. The external illumination angle is theillumination angle in which the illumination angle of the light bundle,which is illuminated from the ophthalmic device 110 toward the subjecteye 12, is prescribed by using the pupil 27 as the reference. Further,the internal illumination angle is the illumination angle in which theillumination angle of the light bundle, which is illuminated toward thefundus of the subject eye 12, is prescribed by using eyeball center O asthe reference. The external illumination angle and the internalillumination angle have a corresponding relationship. For example, in acase in which the external illumination angle is 120°, the internalillumination angle corresponds to approximately 160°.

In a case of forming the objective lens 130 that has a large wide angle(e.g., a UWF (Ultra Wide Field) exceeding 100°) in order to observe thesubject eye 12 in a wide field of view FOV, aberration correction of theobjective lens 130 is important, and there is the tendency for curvingof the image surface, e.g., the Petzval sum, to increase. Thus, in thefirst embodiment, at the ultra wide field objective lens 130, an opticalsystem that can suppress curving of the image surface, e.g., the Petzvalsum, is provided.

Specifically, in the first embodiment, as an example of the ophthalmicoptical system of the present disclosure, the objective lens 130 has thefirst lens group 134 and the second lens group 132 that respectivelyhave positive power, and the third lens group 133, which includes aconcave surface that diverges light, is disposed between the first lensgroup 134 and the second lens group 132. Namely, it suffices to includea concave surface, which is a surface (a diverging surface) at which thedirection in which light diverges is from the glass material into aspace, between the positive first lens group 134 and the positive secondlens group 132. In other words, the objective lens 130 has the positivefirst lens group 134 and the positive second lens group 132 in thatorder from the scanning section side toward the subject eye 12, and thethird lens group 133, which includes a concave surface that divergeslight, is disposed between the first lens group 134 and the second lensgroup 132.

By forming the objective lens 130 in this way, an increase in thePetzval sum of the objective lens 130 can at least be suppressed.

By the way, in a case of forming the objective lens 130 that has a largewide angle (e.g., an ultra wide field (UWF) exceeding 100°) in order toobserve the subject eye 12 in a wide field of view FOV, the lensdiameter increases in accordance with the field angle increasing.Further, accompanying the increase in the lens diameter, the totalamount of the glass material of the lens increases, and the entireweight of the objective lens also increases. Moreover, in a case offorming the objective lens 130, aberration correction of the objectivelens 130 is important, and the operation of the lens system with respectto the pupil that is the object at the objective lens greatly affectsthe aberration correction of the objective lens 130. Thus, in the firstembodiment, an optical system that makes it possible to reduce themaximum aperture of the objective lens 130 is provided. Specifically, inthe first embodiment, as an example of the ophthalmic optical system ofthe present disclosure, by forming the objective lens 130 so as toincorporate an intermediate pupil into the objective lens 130, themaximum aperture of the objective lens 130 is reduced.

In the first embodiment, at the objective lens 130, the intermediatepupil, which is different than the pupil that has a conjugaterelationship with the pupil of the subject eye 12, is formed between thefirst lens group 134 and the second lens group 132, and the third lensgroup 133 is disposed so as to include the position of the intermediatepupil.

Due to the objective lens being structured so as to form an intermediatepupil in this way, while the image forming performance of the objectivelens is improved, an increase in the lens diameter of the objective lens130 can at least be suppressed, and the total weight of the objectivelens 130 due to an increase in the lens diameter can be reduced. Namely,due to the third lens group 133 being disposed so as to include theintermediate pupil position P3 at the objective lens 130, the aberrationcorrection function that is due to the concave surface included in thethird lens group 133 can be improved. Moreover, due to the concavesurface being set near the intermediate pupil position, as compared witha case in which the concave surface is far from the pupil, the divergingoperation at this concave surface can be strengthened more, andcorrection of the Petzval sum is even easier. Accordingly, the variousaberrations, which arise at the second lens group that is nearest to thesubject eye-side and tends to have a large lens diameter, can be easilycorrected by the combining of the first lens group 134 and the thirdlens group 133, and excellent performance can be achieved while the UWFobjective lens as a whole is compact.

By the way, in the structure of the objective lens 130, it is preferablethat the distance to the conjugate position Ps of the pupil of thesubject eye at which the scanning section is provided, and further, thedistance to the subject eye pupil position P2 (the so-called workingdistances) are made to be long. On the other hand, the third lens group133 is positioned between the first lens group 134 and the second lensgroup 132, and there are few constraints on the position thereofprovided that the third lens group 133 is disposed so as to include theintermediate pupil position P3, and the aberration correcting ability ishigh. Thus, as illustrated in FIG. 3 as an example, it is preferablethat the objective lens 130 that is structured so as to form anintermediate pupil be structured so as to satisfy following conditionalexpressions (1), given that the distance between the lens surface, whichis included in the first lens group 134 and is furthest from the subjecteye 12, and the position of the scanning section (the pupil conjugateposition P1 that is the scanning center position Ps) (hereinafter, thisdistance is called the working distance at the scanning section side) isW1, and that the distance between the lens surface, which is furthesttoward the subject eye 12 side at the second lens group 132, and thepupil position P2 of the subject eye (hereinafter, this distance iscalled the working distance at the subject eye 12 side) is W2, and thatthe distance between the concave surface, which is included in the thirdlens group 133 and has the strongest diverging power, and theintermediate pupil position P3 is D.

D<W1,D<W2  (1)

Namely, the intermediate pupil position P3, which is a pupil conjugateposition that is different than the pupil conjugate position P1, isformed between the pupil conjugate position P1 at which the scanningsection is disposed and the subject eye pupil P2, and the gap D, whichis between the intermediate pupil position P3 and concave surface S3that is nearest to the intermediate pupil position P3, is even smallerthan the smallest value among the working distance W1 at the scanningsection side and the working distance W2 at the subject eye 12 side.

By structuring the system in this way, the image forming performance ofthe objective lens 130 can be improved even more.

When considering the aberration of the objective lens 130, it ispreferable to optimize the Petzval image surface. In this case, thePetzval curvature of the lens surface has an effect.

Thus, as illustrated as an example in FIG. 3, given that the Petzvalcurvature of concave surface (diverging surface) S1, which is nearest tothe scanning section in the first lens group 134, is C1, and the Petzvalcurvature of concave surface (diverging surface) S2, which is nearest tothe subject eye in the second lens group 132, is C2, and the Petzvalcurvature of the concave lens surface S3, which has diverging power inthe third lens group 133, is C3, it is preferable that the objectivelens 130 be structured so as to satisfy following conditionalexpressions (2).

C3<C1,C3<C2  (2)

Here, the above-described Petzval curvature C is computed by followingformula (3), where the radius of curvature of that surface is R, and therefractive index of the incident side of that surface N, and therefractive index of the exiting side of that surface is N′.

C={(1/N′)−(1/N)}/(−R)  (3)

Namely, the Petzval curvature C3 of the concave surface S3, which hasthe strongest diverging power among the concave surfaces of the lensesincluded in the third lens group 133, is greater negatively thanwhichever is greater negatively among the Petzval curvature C1 of theconcave surface S1, which has diverging power and is the nearest to thescanning section among the lenses included in the first lens group 134,and the Petzval curvature C2 of the concave surface S2, which hasdiverging power and is the nearest to the subject eye 12 among thelenses included in the second lens group 132.

By structuring the system in this way, the image forming performance ofthe objective lens 130 can be improved even more. Namely, by providingthe third lens group 133 that has the pupil conjugate image at theobjective lens 130, the strong diverging surface S3 can be provided in avicinity of the pupil conjugate point at this third lens group 133.Further, by structuring the Petzval curvature C3 as described above, ascompared with an objective lens that does not have the third lens group133 that has a pupil conjugate image, the Petzval sum of the objectiveoptical system overall that includes the objective lens 130 can be madeto be small, and an extremely excellent image forming performance can beachieved.

When considering the maximum aperture of the objective lens 130, thelens that is included in the second lens group 132 that is at thesubject eye side has a great effect. On the other hand, in a case offorming the system such that the intermediate pupil is incorporated intothe objective lens 130 by the third lens group 133, the apertures of thelenses included in the third lens group 133 are greater than the secondlens group 132, and therefore, the factor that limits reduction of themaximum aperture of the objective lens 130 is the apertures of thelenses that are included in the third lens group 133, and this is anobstacle to reducing the maximum aperture of the objective lens 130.

Thus, given that the maximum effective diameter of the lenses includedin the first lens group 134 is φ1, and the maximum effective diameter ofthe lenses include in the second lens group 132 is φ2, and the maximumeffective diameter of the lenses included in the third lens group 133 isφ3, it is preferable that the objective lens 130 be structured so as tosatisfy following conditional expression (4).

φ3,φ1<0.7·φ2  (4)

Namely, the maximum effective diameter φ1 of the lenses included in thefirst lens group 134 and the maximum effective diameter φ3 of the lensesincluded in the third lens group 133 both are less than 70% of themaximum effective diameter φ2 of the lenses included in the second lensgroup 132.

By structuring the system in this way, the objective lens 130 can bemade to be compact and lightweight.

In accordance with the above-described first embodiment, by structuringthe objective lens 130 that satisfies the above-described conditions,the scanning center position Ps of the scanning section (the pupilconjugate position P1) is transferred to the pupil of the subject eye(the pupil position P2) by the objective lens 130. Further, at theobjective lens 130, conjugate point Po of the pupil (the intermediatepupil position P3) is formed within the third lens group 133, and theconjugate point Po (the intermediate pupil position P3) is conjugatewith the scanning center position Ps (the pupil conjugate position P1)as well. The concave surface (i.e., the diverging surface) at thisconjugate point Po (intermediate pupil position P3) is extremelyeffective in aberration correction (effective in correcting the Petzvalsum) of the overall objective lens 130, and the image formingperformance of the objective lens 130 can be improved greatly. Further,the apertures of the first lens group 134 and the second lens group 132can be made to be small, and the objective lens 130 overall can,although UWF, be made to be compact and lightweight.

Note that, in the first embodiment, a case is described in which lightis scanned by the horizontal scanning section 142 and the verticalscanning section 148, and polygon mirrors and galvano mirrors are givenas examples of the horizontal scanning section 142 and the verticalscanning section 148. However, the technique of the present disclosureis not limited to this. For example, another optical element that canscan scanning light in the Y direction may be used, and examples thereofare a MEMS (Micro-electromechanical system) mirror, a rotating mirror, aprism, and a resonant mirror.

Further, with regard to the scanning of the scanning light in the firstembodiment, similar scanning can, of course, be carried out even if theX direction and the Y direction are switched.

SUITABLE EXAMPLES

Examples of the objective lens 130 of the technique of the presentdisclosure are described next.

Example 1

An example of the lens structure of the objective lens 130 relating toExample 1 is illustrated in FIG. 4. The objective lens 130 is arefractive optical system that includes the lenses L11˜L34.

FIG. 4 illustrates the pupil conjugate position P1 that is common to thescanning center position Ps of the scanning section, the pupil positionP2 of the subject eye 12, and the intermediate pupil position P3 that isthe conjugate point Po of the pupil. Note that P1, P2 and P3 in thedrawing are illustrated in order to illustrate positions in the opticalaxis direction, and the drawing is not intended to illustrate the shapesand sizes thereof. The objective lens 130 includes, in order from thescanning section side, the first lens group 134 (G1) and the second lensgroup 132 (G2). Further, the third lens group 133 (G3) is disposedbetween the first lens group 134 (G1) and the second lens group 132(G2). As described above, the intermediate pupil position P3 is formedwithin the third lens group 133 (G3) that serves as an intermediategroup. The light beams illustrated in FIG. 4 are the main light beams ofscanning light bundles of the maximum angle that are incident on thepupil P2 of the subject eye, and this is clear from the fact that theselight beams intersect in the third lens group 133 (G3).

In the following description, there are cases in which the first lensgroup 134 is called first lens group G1, the second lens group 132 iscalled second lens group G2, and the third lens group 133 is calledthird lens group G3. Note that, in the example illustrated in FIG. 4,the third lens group G3 is disposed in the space that is separated byair gaps between the first lens group G1 and the second lens group G2,and, within the objective lens 130, the air gap between the third lensgroup G3 and the second lens group G2 is the longest air gap.

The first lens group G1 includes, in order from the pupil conjugateposition P1 side that is the scanning section side toward the subjecteye 12 side, the positive meniscus lens L11 whose concave surface facesthe scanning section side, the negative lens L12 having a concavesurface at the scanning section side, the positive lens L13, thepositive lens L14 and the negative lens L15. The lens L12 and the lensL13 are cemented together, and form a lens component that is shaped as ameniscus lens whose concave surface faces the scanning section side.Further, the lens L14 and the lens L15 are cemented together, and form alens component that is shaped as a meniscus lens whose convex surfacefaces the scanning section side.

The second lens group G2 includes, in order from the scanning sectionside toward the subject eye side, the positive lens L21, the positivelens L22, the negative lens L23 and the positive meniscus lens L24 whoseconvex surface faces the scanning section side. The lens L22 and thelens L23 are cemented together, and form a lens component that is shapedas a meniscus lens whose concave surface faces the subject eye 12 side.

The third lens group G3 includes, in order from the scanning sectionside toward the subject eye side, the positive lens 31, the negativelens L32, the meniscus lens L33 whose convex surface faces the scanningsection side, and the meniscus lens L34 whose concave surface faces thescanning section side. The lens L31 and the lens L32 are cementedtogether, and form a lens component that is shaped as a meniscus lens.Here, the concave lens surface S3, which has the strongest divergingpower of the above-described third lens group G3, is the concave surfaceat the subject eye side of the negative lens L33.

Lens data of Example 1 is illustrated in Table 1. The lens dataillustrates, in order from the left column, the surface number (No.),the radius of curvature, the surface gap on the optical axis, therefractive index (Nd) based on the d line (wavelength 587.56 nm), andthe Abbe number (vd) based on the d line. The 1st surface of the lensdata is the pupil conjugate position P1 that is common to the scanningcenter position Ps of the scanning section, and is listed as the“aperture” of an imaginary plane (whose radius of curvature is listed asinf) in the table. The value in the final row of the surface gap columnexpresses the distance, on the optical axis, from the lens surface thatis furthest toward the subject eye side in the table to the pupilposition P2. Note that, because the objective lens 130 is an afocalsystem, the listings in this table assume a case in which the object isset at infinity. Further, the 7th surface, the 11th surface, the 15thsurface and the 20th surface are imaginary planes for performanceevaluation of the objective lens 130, and do not in any way affect thatlight beam that passes therethrough.

TABLE 1 radius of surface No. curvature gap Nd νd object inf infaperture inf 46.955 2 −42.7608 8.707 1.740770 27.74 3 −30.7098 8.932 4−224.721 5.304 1.755200 27.57 5 36.51584 24.840 1.518230 58.82 6−49.1996 0.500 7 inf 0.000 8 52.47307 31.323 1.744000 44.8 9 −45.23375.073 1.698950 30.13 10 78.21317 25.000 11 inf 66.256 12 17.57037 12.6981.744000 44.8 13 −20.7392 5.447 1.755200 27.57 14 7.885318 2.866 15 inf5.000 16 14.05853 13.432 1.755200 27.57 17 17.06274 1.361 18 −24.78947.511 1.749500 35.25 19 −14.3036 159.920 20 inf 45.000 21 474.851226.060 1.620410 60.25 22 −118.393 0.500 23 81.6612 43.103 1.620410 60.2524 −83.0378 5.000 1.805180 25.45 25 573.9011 0.500 26 36.91632 23.7031.744000 44.8 27 61.01281 25.000

FIG. 5 is a lateral aberration graph of the objective lens that isstructured by the various items of Table 1. In the lateral aberrationgraph of FIG. 5, image height is on the vertical axis, the solid lineillustrates a wavelength of 850.0 nm, the dashed line illustrates 633.0nm, the one-dot chain line illustrates 532.0 nm, and the two-dot chainline illustrates 486.1327 nm.

As is clear from the lateral aberration graph illustrated in FIG. 5, itis confirmed that, at the objective lens 130 of Example 1, thedispersion in aberration with respect to lights of a wide wavelengthregion, which includes light of the visible light wavelength region andlight of the near infrared region, is suppressed and is corrected well.

Example 2

An example of the lens structure of the objective lens 130 relating toExample 2 is illustrated in FIG. 6. Note that, because Example 2 has astructure that is similar to Example 1, the same portions are denoted bythe same reference numerals, and detailed description thereof isomitted.

The first lens group G1 includes, in order from the pupil conjugateposition P1 side that is the scanning section side toward the subjecteye side, the positive meniscus lens L11 whose convex surface faces thescanning section side, the negative lens L12 having a concave surface atthe subject eye 12 side, the positive meniscus lens L13 whose concavesurface faces the scanning section side, the positive meniscus lens L14whose convex surface faces the scanning section side, and the positivelens 15. The lens L14 and the lens L15 are cemented together, and form alens component of a biconvex shape.

The second lens group G2 includes, in order from the scanning sectionside toward the subject eye side, the positive lens L21, the positivelens L22, the negative lens L23 and the positive meniscus lens L24 whoseconvex surface faces the scanning section side. The lens L22 and thelens L23 are cemented together, and form a lens component that is shapedas a meniscus lens whose concave surface faces the subject eye 12 side.

The third lens group G3 includes, in order from the scanning sectionside toward the subject eye side, the positive lens 31, the negativemeniscus lens L32 whose concave surface faces the scanning section side,the lens L33 whose convex surface faces the scanning section side, andthe meniscus lens L34 whose convex surface faces the subject eye 12side. The lens L31 and the lens L32 are cemented together, and form apositive lens component. Here, the concave lens surface S3, which hasthe strongest diverging power of the above-described third lens groupG3, is the concave surface at the subject eye side of the negative lensL33.

Lens data of Example 2 is illustrated in Table 2.

TABLE 2 radius of surface No. curvature gap Nd νd object inf infaperture inf 20.000 2 30.12349 6.632 1.785900 44.17 3 62.11636 10.184 4−335.629 5.000 1.846660 23.8 5 35.49029 6.949 6 −69.3516 10.485 1.75500052.34 7 −27.9288 0.500 8 204.6868 5.000 1.698950 30.13 9 31.00309 23.4711.755000 52.34 10 −74.2074 30.000 11 inf 54.116 12 46.2911 16.9021.755000 52.34 13 −32.6508 5.000 1.846660 23.8 14 −364.222 26.645 1511.66935 7.439 1.850260 32.35 16 7.539325 4.349 17 −14.4018 16.7641.640000 60.19 18 −15.1784 166.985 19 inf 46.561 20 245.4849 28.1611.620410 60.25 21 −191.188 0.500 22 84.21076 50.485 1.620410 60.25 23−113.415 5.000 1.846660 23.8 24 447.2304 0.500 25 40.128 27.364 1.75499852.32 26 61.01281 25.000

FIG. 7 is a lateral aberration graph of the objective lens that isstructured by the various items of Table 2.

As is clear from the lateral aberration graph illustrated in FIG. 7, itis confirmed that, at the objective lens 130 of Example 2, thedispersion in aberration with respect to lights of a wide wavelengthregion, which includes light of the visible light wavelength region andlight of the near infrared region, is suppressed and is corrected well.

Example 3

An example of the lens structure of the objective lens 130 relating toExample 3 is illustrated in FIG. 8. Note that, because Example 3 has astructure that is similar to Example 1, the same portions are denoted bythe same reference numerals, and detailed description thereof isomitted.

The first lens group G1 includes, in order from the pupil conjugateposition P1 side that is the scanning section side toward the subjecteye 12 side, the positive meniscus lens L11 whose concave surface facesthe scanning section side, the negative lens L12, the positive lens L13,the positive lens L14, and the negative lens L15 whose concave surfacefaces the scanning section side. The lens L12 and the lens L13 arecemented together, and form a lens component that is shaped as ameniscus lens whose concave surface faces the scanning section side.Further, the lens L14 and the lens L15 are cemented together, and form alens component that is shaped as a meniscus lens whose convex surfacefaces the scanning section side.

The second lens group G2 includes, in order from the scanning sectionside toward the subject eye side, the positive lens L21, the positivelens L22, the negative lens L23 and the positive meniscus lens L24 whoseconvex surface faces the scanning section side. The lens L22 and thelens L23 are cemented together, and form a lens component that is shapedas a meniscus lens whose convex surface faces the scanning section side.

The third lens group G3 includes, in order from the scanning sectionside toward the subject eye side, the positive lens 31, the negativelens L32, the meniscus lens L33 whose concave surface faces the scanningsection side, and the meniscus lens L34 whose concave surface faces thescanning section side. The lens L31 and the lens L32 are cementedtogether, and form a lens component that is shaped as a meniscus lenswhose convex surface faces the scanning section side. Here, the concavelens surface S3, which has the strongest diverging power of theabove-described third lens group G3, is the concave surface at thesubject eye side of the meniscus lens L33.

Lens data of Example 3 is illustrated in Table 3.

TABLE 3 radius of surface No. curvature gap Nd Nd object inf infaperture inf 45.000 2 −42.4275 8.993 1.700000 48.1 3 −29.6815 10.321 4−145.84 5.000 1.795040 28.69 5 39.26125 23.733 1.579570 53.74 6 −51.5791.575 7 77.20313 30.604 1.744000 44.8 8 −35.9779 5.000 1.698950 30.13 9−36628.8 30.000 10 inf 54.000 11 18.21663 9.908 1.834000 37.18 12−18.5816 15.403 1.846660 23.8 13 14.15261 1.457 14 −6.90368 5.5261.902000 25.26 15 −8.39297 18.701 16 −44.3231 25.181 1.743200 49.26 17−41.3408 122.844 18 inf 54.728 19 299.3385 23.025 1.696797 55.53 20−224.23 0.500 21 84.28155 51.896 1.696797 55.53 22 −102.322 5.0001.846660 23.8 23 192.8745 0.500 24 40.93564 26.098 1.883000 40.66 2561.01281 25.000

FIG. 9 is a lateral aberration graph of the objective lens that isstructured by the various items of Table 3.

As is clear from the lateral aberration graph illustrated in FIG. 9, itis confirmed that, at the objective lens 130 of Example 3, thedispersion in aberration with respect to lights of a wide wavelengthregion, which includes light of the visible light wavelength region andlight of the near infrared region, is suppressed and is corrected well.

Example 4

An example of the lens structure of the objective lens 130 relating toExample 4 is illustrated in FIG. 10. Note that, because Example 4 has astructure that is similar to Example 1, the same portions are denoted bythe same reference numerals, and detailed description thereof isomitted.

The first lens group G1 includes, in order from the pupil conjugateposition P1 side that is the scanning section side toward the subjecteye 12 side, the negative meniscus lens L11 whose convex surface facesthe scanning section side, the positive lens L12, the negative lens L13,the positive lens L14 and the positive lens L15. The lens L11 and thelens L12 are cemented together, and form a positive lens componenthaving a biconvex shape. Further, the 9th surface, which is the surfaceat the subject eye 12 side of the lens L15, is formed by an asphericalsurface.

The second lens group G2 includes, in order from the scanning sectionside toward the subject eye side, the positive lens L21, the positivelens L22, the negative lens L23 and the positive meniscus lens L24 whoseconvex surface faces the scanning section side. The lens L22 and thelens L23 are cemented together, and form a lens component that is shapedas a meniscus lens whose convex surface faces the scanning section side.

The third lens group G3 includes, in order from the scanning sectionside toward the subject eye side, the positive lens 31, the negativemeniscus lens L32 whose concave surface faces the scanning section side,the meniscus lens L33 whose convex surface faces the scanning sectionside, the negative lens 34 and the positive lens 35. The lens L31 andthe lens L32 are cemented together, and form a positive lens componenthaving a biconvex shape. The lens L34 and the lens L35 are cementedtogether, and form a lens component that is shaped as a meniscus lenswhose concave surface faces the scanning section side. Here, the concavelens surface S3, which has the strongest diverging power of theabove-described third lens group G3, is the concave surface at thesubject eye side of the negative lens L33.

Lens data of Example 4 is illustrated in Table 4.

TABLE 4 radius of surface No. curvature gap Nd Nd object 1.00E+181.00E+20 aperture 1.00E+18 45.000 2 56.34893 5.000 1.755200 27.57 333.2776 21.815 1.622800 57.1 4 −49.7487 0.500 5 −386.18 5.000 1.75520027.57 6 36.34466 5.521 7 87.77264 13.353 1.620410 60.25 8 −50.9255 0.5489 aspherical 57.4878 9.271 1.487490 70.32 surface 10 1.65E+17 25.000 111.00E+18 55.000 12 42.40217 11.666 1.487490 70.32 13 −24.0717 5.0001.755200 27.57 14 −59.5375 0.500 15 14.13321 18.840 1.744000 44.8 168.65902 1.531 17 −14.5189 24.664 1.795040 28.69 18 43.25015 14.3831.688930 31.16 19 −23.569 135.347 20 1.00E+18 58.712 21 490.9155 24.7601.620410 60.25 22 −176.971 0.500 23 92.26245 56.343 1.620410 60.25 24−100.651 5.000 1.755200 27.57 25 1170.956 0.500 26 39.79969 31.2391.620410 60.25 27 61.01281 25.000

At the aspherical surface listed in Table 4, given that the height inthe direction orthogonal to the optical axis is h, the distance (sagamount) along the optical axis from the tangent plane at the apex of theaspherical surface to the position on the aspherical surface at heighthis zs, the inverse of the radius of curvature of the near axis is c,the constant of the cone is k, the 4th-order aspherical coefficient isA, the 6th-order aspherical coefficient is B, the 8th-order asphericalcoefficient is C, the 10th-order aspherical coefficient is D and the12th-order aspherical coefficient is E, zs is expressed by the followingformula.

zs=(c·h ²)/[1+{1−(1+k)·h ² ·c ²}^(1/2)]A·h ⁴ +B·h ⁶ +C·h ⁸ +D·h ¹⁰ +E·h¹²

The aspherical coefficients of the aspherical surfaces in Example 4 arelisted in Table 5. In the table, the aspherical coefficients from A onare listed as the orders. “E−n” (n is an integer) in the table means“×10^(−n)”.

TABLE 5 surface 9: aspherical surface conic constant 0 4th-order−2.5207E−05 6th-order  3.0418E−07 8th-order −2.2241E−09 10th-order 1.0231E−11 12th-order −3.0965E−14 14th-order  6.1327E−17 16th-order−7.6047E−20 18 th-order  5.3451E−23 20th-order −1.6247E−26

FIG. 11 is a lateral aberration graph of the objective lens that isstructured by the various items of Table 4 and Table 5.

As is clear from the lateral aberration graph illustrated in FIG. 11, itis confirmed that, at the objective lens 130 of Example 4, thedispersion in aberration with respect to lights of a wide wavelengthregion, which includes light of the visible light wavelength region andlight of the near infrared region, is suppressed and is corrected well.

Next, the conformance of the above conditional expressions with theobjective lenses in the respective Examples of above-described Example 1through Example 4 is described. Values relating to the above conditionalexpressions for Example 1 through Example 4 respectively are listed inTable 6.

TABLE 6 Example 1 Example 2 Example 3 Example 4 D 13.82 (14) 3.31 (16)1.93 (14) 5.26 (16) (surface no.) W1 46.95 20.00 45.00 45.00 W2 25.0025.00 25.00 25.00 C1 −0.00995 0.0146 −0.00971 0.00764 C2 −0.00699−0.00705 −0.00769 −0.00628 C3 −0.05457 −0.061 −0.0687 −0.0493 ϕ1 68 5365 49 ϕ2 125 140 134 144 ϕ3 24 39 43 35 M 2.1 2.1 2.2 2.1 f3 64.01 73.5661.92 63.13

As is clear from Table 6, it is clear that the objective lenses ofExample 1 through Example 4 are in conformance with the aboveconditional expressions.

Second Embodiment

A second embodiment is described next. In the second embodiment, theobjective lens 130, which is the main portion of the imaging opticalsystem 116A relating to the first embodiment, is formed as an attachedoptical system, and can be attached to and removed from a portableterminal that has an imaging function. Because the structure of thesecond embodiment is substantially similar to the first embodiment, thesame portions are denoted by the same reference numerals, anddescription thereof is omitted, and mainly the portions that aredifferent are described.

FIG. 12 illustrates an example of a structure in which an attachedoptical system 300 relating to the second embodiment can be attached toand removed from a portable terminal 400 that has an imaging function.

As illustrated in FIG. 12, the portable terminal 400 has an imagingsection 402 for realizing the imaging function. The imaging section 402operates in a usual imaging mode, in which the imaging section 402captures an image of a subject at infinity such as a landscape or thelike, by user operation of an unillustrated operation portion that theportable terminal 400 has. Namely, the imaging section 402 of theportable terminal 400 has a lens 404 for a portable terminal (FIG. 13),and is structured so as to, by operation in the usual imaging mode, forman image on an imaging element 406 (FIG. 13) when parallel light isincident.

FIG. 13 illustrates an example of the structure of the attached opticalsystem 300 relating to the second embodiment. A state in which theattached optical system 300 is attached to the portable terminal 400 isillustrated in FIG. 13. The attached optical system 300 has the firstlens group G1, the second lens group G2 and the third lens group G3 thatstructure the above-described objective lens 130. Because the structuresand functions of these respective lens groups are similar to the firstembodiment, detailed description thereof is omitted.

At the attached optical system 300 relating to the second embodiment,the point that an illuminating portion 304 that emits illuminationlight, and a half mirror 302 that guides the illumination light that isfrom the illuminating portion to the optical path that runs along theoptical axis AX, are provided at the objective lens 130 relating to thefirst embodiment, is different. The illuminating portion 304 emits theillumination light that illuminates the subject eye 12. The half mirror302 guides the illumination light that is from the illuminating portion304 to the optical path that runs along the optical axis AX.

Note that, in a case in which the portable terminal 400 has a subjectilluminating portion that illuminates the subject, it suffices for theattached optical system 300 to, instead of the illuminating portion 304and the half mirror 302, employ the illumination light that is emittedfrom the subject illuminating portion, and have an optical system thatguides the illumination light that is from the subject illuminatingportion to the optical path that runs along the optical axis AX.Further, the illuminating portion 304 may be an independent structure,and not be provided at the attached optical system 300.

The attached optical system 300 has an attaching portion 306 thatattaches the attached optical system 300 to the portable terminal 400,in order to form a structure in which the attached optical system 300and the portable terminal 400 can be attached and removed. Due to theattached optical system 300 having this attaching portion 306, astructure in which the attached optical system 300 can be attached toand removed from the portable terminal 400 becomes possible.

The first lens group G1 and the second lens group G2 that are includedin the attached optical system 300 function as an objective opticalsystem 301 that forms a pupil that has a conjugate relationship with thepupil of the subject eye 12. The attached optical system 300 and theportable terminal 400 are fixed by the attaching portion 306 such thatthe incident pupil of the imaging section 402 of the portable terminal400 is positioned at the position (the pupil conjugate position P1) ofthe pupil that is in a conjugate relationship with the pupil of thesubject eye 12 formed by the objective optical system 301.

By structuring the system in this way, a fundus image of the subject eye12 can be imaged by the simple structure of merely attaching theattached optical system 300 to the portable terminal 400.

Third Embodiment

A third embodiment is described next.

In the first embodiment, the imaging optical system 116A, whichfunctions as a posterior eye portion observing optical system thatobserves the posterior eye portion of the subject eye 12, is mainlydescribed. The third embodiment is formed so as to be able to switch soas to function as an anterior eye portion observing optical system thatobserves the anterior eye portion of the subject eye 12, by inserting anoptical module for anterior eye portion observation into the imagingoptical system 116A that functions as the posterior eye portionobserving optical system relating to the first embodiment. Because thestructure of the third embodiment is substantially similar to the firstembodiment, the same portions are denoted by the same referencenumerals, and description thereof is omitted, and the portions thatdiffer are mainly described.

FIG. 14 illustrates an example of the structure of the objective lens130 at the imaging optical system 116A relating to the third embodiment.The imaging optical system 116A relating to the third embodiment has theobjective lens 130 that can switch between a posterior eye portionobserving optical system and an anterior eye portion observing opticalsystem. The objective lens 130 has, in order from the scanning section(e.g., the horizontal scanning section 142) side, the first lens group134 and the second lens group 132, and has the third lens group 133 inthe space between the first lens group 134 and the second lens group132. The structures of these first lens group 134 (G1), second lensgroup 132 (G2) and third lens group 133 (G3) are similar to the firstembodiment, and therefore, detailed description thereof is omitted.

The imaging optical system 116A has an optical module 136 for anterioreye portion observation that can be inserted onto and removed from theoptical path of the objective lens 130. Due to the optical module foranterior eye portion observation being placed on the optical path of theobjective lens 130, the imaging optical system 116 can switch from anoptical system for posterior eye portion observation to an opticalsystem for anterior eye portion observation. Specifically, asillustrated in FIG. 14, the optical module 136 for anterior eye portionobservation is inserted onto the optical path of the objective lens 130,e.g., on the optical path between the first lens group 134 (G1) that haspositive refractive power and the second lens group 132 (G2) that haspositive refractive power, which structure the objective lens 130.Preferably, as illustrated in FIG. 14, the optical module 136 foranterior eye portion observation is inserted between the second lensgroup 132 (G2) and the third lens group 133 (G3).

The optical module 136 has, at the interior thereof, an optical elementincluding a lens 162 that serves as a switching lens and has negativepower. When the lens 162 is placed on the optical axis of the objectivelens 130, the lens 162 operates as a switching lens for switching aposterior eye portion observing optical system 300 to an anterior eyeportion observing optical system 400. In a case in which the lens 162 isinserted on the optical path of the objective lens 130, the scanningposition (the scanning center position Ps) of the scanning section(e.g., the horizontal scanning section 142) and the pupil position P3 ofthe subject eye 12 are not conjugate, and the parallel light from thescan position of the scanning section is collected at the anterior eyeportion. The diameter of the light bundle that passes through the lens162 is smaller than the diameters of the light bundles that pass throughthe first lens group 134 and the second lens group 132, respectively.Accordingly, the effective diameter of the lens 162 is small as comparedwith the effective diameters of the lens groups that structure theobjective lens 130. Therefore, the optical module 136 can be structuredto be compact. Note that the optical element is not limited to the lens162 that has negative power, and, instead of the lens 162, an opticalmember such as, for example, a Fresnel lens, a DOE (Diffractive OpticalElement) or the like may be used.

More specifically, the imaging optical system 116A is a structure inwhich the optical module 136 for anterior eye portion observation can beinserted onto and removed from the optical path of the objective lens130, which is the optical path of an observing optical system forposterior eye portion observation, either manually by an operator (e.g.,an ophthalmologist) or automatically. In a case in which the opticalmodule 136 is not disposed on the optical path of the objective lens130, a posterior eye portion observing optical system is structured asthe observing optical system, and the ophthalmic device 110 acquires animage of the posterior eye portion of the subject eye 12 thereby. On theother hand, in a case in which the optical module 136 is inserted on theoptical path of the objective lens 130, an anterior eye portionobserving optical system is structured as the observing optical system,and the ophthalmic device 110 acquires an image of the anterior eyeportion of the subject eye 12 thereby.

Note that the optical module 136 for anterior eye portion observationmay have an eye tracking module that tracks the sightline direction andis used at the time of anterior eye portion observation, a fixation lampthat guides the sightline direction of the subject eye 12, a camera, andan illumination device.

As described above, in accordance with the third embodiment, byinserting and removing the optical module 136 for anterior eye portionobservation onto and from the optical path of the objective lens 130that functions as an observing optical system for posterior eye portionobservation, the imaging optical system 116A can be instantaneouslyswitched between an anterior eye portion observing optical system thatobserves the anterior eye portion of the subject eye 12 and a posterioreye portion observing optical system that observes the posterior eyeportion.

Suitable Example

An Example of the objective lens 130 relating to the third embodiment isdescribed next.

Example 5

FIG. 15 illustrates an example of the lens structure of the objectivelens 130 relating to Example 5. Note that, because Example 5 has astructure that is similar to Example 2, the same portions are denoted bythe same reference numerals, and detailed description thereof isomitted. In Example 5, the point that the lens 136 that is included inthe optical module 136 for anterior eye portion observation is addedbetween the second lens group 132 and the third lens group 133 in thestructure of Example 2, is different.

In Example 5, a negative lens L41 is disposed between the second lensgroup G2 and the third lens group 133, and specifically, between thepositive lens L21 and the negative lens L34.

Lens data of Example 5 is illustrated in Table 7.

TABLE 7 radius of surface curvature gap Nd Nd object inf inf apertureinf 20.000 2 30.12349 6.632 1.785900 44.17 3 62.11636 10.184 4 −335.6295.000 1.846660 23.8 5 35.49029 6.949 6 −69.3516 10.485 1.755000 52.34 7−27.9288 0.500 8 204.6868 5.000 1.698950 30.13 9 31.00309 23.4711.755000 52.34 10 −74.2074 30.000 11 inf 54.116 12 46.2911 16.9021.755000 52.34 13 −32.6508 5.000 1.846660 23.8 14 −364.222 26.645 1511.66935 7.439 1.850260 32.35 16 7.539325 4.349 17 −14.4018 16.7641.640000 60.19 18 −15.1784 104.193 19 inf 3.500 1.516800 63.8807 20−25.7000 105.853 21 245.4849 28.161 1.620410 60.25 22 −191.188 0.500 2384.21076 50.485 1.620410 60.25 24 −113.415 5.000 1.846660 23.8 25447.2304 0.500 26 40.128 27.364 1.754998 52.32 26 61.01281 25.000

Although not illustrated, at the objective lens 130 of Example 5, evenin a case in which the optical module 136 for anterior eye portionobservation is inserted on the optical path of the objective lens 130that functions as an observing optical system for posterior eye portionobservation, aberration with respect to lights of the wavelength regionfor anterior eye portion imaging (the visible light wavelength region orthe near infrared region) is corrected well.

Fourth Embodiment

A fourth embodiment is described next. Because the structure of thefourth embodiment is substantially similar to the above-describedembodiments, the same portions are denoted by the same referencenumerals, and description thereof is omitted.

In the above-described embodiments, the objective lens 130, which isincluded in the imaging optical system 116A for observing the subjecteye 12, can suppress the dispersion in aberration with respect to lightsof a wide wavelength region, which includes light of the visible lightwavelength region and light of the near infrared region. Accordingly,the objective lens 130 relating to the above-described respectiveembodiments can be applied to ophthalmic devices that are exclusivelyused for SLO and OCT, respectively. In addition, in a combined devicethat has both functions of SLO and OCT, the objective lens 130 can beused as an objective lens shared by SLO and OCT (can be used for both).In the fourth embodiment, the objective lens 130 is used in common forSLO and OCT.

Because the wavelengths of the lights that are used are different in anoptical system for SLO and an optical system for OCT, it is preferableto adjust the lens structures to as to accord with them respectively.Thus, in the fourth embodiment, because the objective lens 130 is usedin common, the objective lens is structured by two lens groups, and theobjective lens for SLO is made to be the reference, and the differencebetween the optical system for SLO and the optical system for OCT isabsorbed by one lens group (e.g., the first lens group G1).Specifically, by structuring the objective lens by two lens groups, andusing the front lens group (the second lens group G2) in common, andchanging the structure of the rear lens group (the first lens group G1),the system is structured so as to switch from functioning as a relaylens device for SLO to functioning as a relay lens device for OCT.

FIG. 16 illustrates an example of the structure of the objective lens130 in the imaging optical system 116A relating to the fourthembodiment.

As illustrated in FIG. 16, at the objective lens 130 relating to thefourth embodiment, a region that propagates substantially parallel lightis formed on the optical path, and a splitting/combining element (e.g.,a dichroic mirror) DM1, which splits and combines the optical path atthe formed region, is provided. In the example illustrated in FIG. 16,an optical system is formed at a parallel system between the first lensgroup G1 and the third lens group G3. In this case, the first lens groupG1 is a lens group such that the light, which heads from the first lensgroup G1 toward the third lens group G3, becomes a parallel system.

Further, the third lens group G3 is a lens group such that the light ofthe parallel system from the first lens group G1 includes theintermediate pupil position P3. Specifically, the third lens group G3includes, in order from the scanning section side, a lens group G31, alens group G32 and a lens group G33. The lens group G31 is a lens grouphaving the function of forming an intermediate pupil at the interior ofthe third lens group G3, from the light of the parallel system from thefirst lens group G1. The lens group G32 is a lens group having a concavesurface at the intermediate pupil position P3 or in a vicinity thereof.The lens group G33 is a lens group having the function of transferringthe intermediate pupil toward the second lens group.

For example, the optical path that includes the optical axis AXillustrated in FIG. 16 is used as the SLO optical path, and thesplitting/combining element DM1 is disposed at a region between thefirst lens group G1 and the third lens group G3, and is used at the OCToptical path. By doing so, the two optical systems of SLO and OCT can becombined. In this way, in the fourth embodiment, by forming a region,which propagates substantially parallel light, on the optical path ofthe objective lens 130, and disposing the splitting/combining elementDM1, which splits the optical path, at the formed region, the twooptical paths of SLO and OCT can be combined.

The fourth embodiment describes a case of using an OCT optical pathformed by a dichroic mirror or the like at a region that propagatessubstantially parallel light. However, the region that propagatessubstantially parallel light is not limited to a region between thefirst lens group G1 and the third lens group G3. For example, asplitting/combining element may be provided in any space between thefirst lens group G1 and the third lens group G3 of the objective lenses130 relating to the above-described respective embodiments. Further,although the fourth embodiment describes a case in which thesplitting/combining element DM1 is disposed at a region that propagatessubstantially parallel light, the fourth embodiment is not limited tothis. For example, a splitting/combining element DM2 may be disposed ata region between the lens group G31 and the lens group G32 at the thirdlens group G3, or a splitting/combining element DM3 may be disposed at aregion between the lens group G32 and the lens group G33, or asplitting/combining element DM4 may be disposed at a region between thethird lens group G3 and the second lens group G2.

In the structure illustrated in FIG. 16, of course, the optical paththat includes the optical axis AX may be used as the OCT optical path,and the splitting/combining element DM1 may be placed and used at theSLO optical path.

Note that, when an optical element (the splitting/combining element DM4)is placed between the second lens group G2 and the third lens group G3,there are cases in which flares arise in the visible light region.Therefore, in a case in which an optical element (thesplitting/combining element DM4) is placed between the second lens groupG2 and the third lens group G3, and the optical path is split, it ispreferable to use a splitting optical path as the OCT optical path.

In this way, in accordance with the fourth embodiment, the objectivelens 130 can be used also as a combined device that has the functions ofboth SLO and OCT.

Fifth Embodiment

A fifth embodiment is described next. Because the structure of the fifthembodiment is substantially similar to the fourth embodiment, the sameportions are denoted by the same reference numerals, and descriptionthereof is omitted.

There are cases in which an ophthalmic device has both a fixation targetprojecting optical system that provides a fixation target by a fixationlamp, and an subject eye position imaging optical system that capturesan image of the position of the subject eye 12 by a camera or the like.At these observing optical systems such as the fixation targetprojecting optical system and the subject eye position imaging opticalsystem or the like, the image forming performance is sufficient mainlyby appropriately carrying out correction with respect to the visibleregion. On the other hand, at the objective lens 130 of the presentdisclosure, correction of aberration in a wide wavelength region thatincludes both the visible region for SLO and the near infrared regionfor OCT is extremely good. In this case, the system can be structuredsuch that aberration correction in mainly the visible region is carriedout at further toward the subject eye 12 side than the pupil conjugateposition P3 in the objective lens 130, and aberration correction in thenear infrared region is carried out by an optical system that is furthertoward the scanning system side than the pupil conjugate position P3.Namely, for the aberration correction, the wavelength region is dividedinto plural regions, and aberration correction for the differentwavelength regions can be carried out respectively thereat. For example,the second lens group G2 is used as the optical system that is furthertoward the subject eye 12 side than the intermediate pupil conjugateposition P3, and the first lens group G1 is used as the optical systemthat is further toward the scanning section side than the intermediatepupil conjugate position P3. Further, in a case of combining the opticalpaths of the observing optical systems such as the fixation targetprojecting optical system and the subject eye position imaging opticalsystem and the like, a prism for optical path combining can be disposedwithin the third lens group G3 at a region before or after the pupilconjugate position P3 (the region where the splitting/combining elementDM2 or DM3 illustrated in FIG. 16 is disposed). In a case of giving moreconsideration to the effects of aberration in the visible region, it ispreferable to place the prism for optical path combining, which combinesthe optical paths, at the region where the splitting/combining elementDM3 is disposed. Further, in a case of using infrared light in thesubject eye position imaging optical system, it is effective to providethe prism for optical path combining at the position of DM1 that is atthe scanning section side in FIG. 16. In either case, in a case ofproviding a prism for optical path combining between the subject eyepupil P2 and the pupil conjugate position P1 at which the scanningsection is disposed, it is important to adjust the balance of theaberration correcting functions at the respective groups of theobjective lens that is structured to include three groups.

In this way, in accordance with the fifth embodiment, observing opticalsystems such as the fixation target projecting optical system and thesubject eye position imaging optical system and the like can be providedat the ophthalmic device 110 by a simple structure.

Sixth Embodiment

A sixth embodiment is described next. Because the structure of the sixthembodiment is substantially similar to the above-described embodiments,the same portions are denoted by the same reference numerals, anddescription thereof is omitted.

In the above-described embodiments, the objective lens 130, which isincluded in the imaging optical system 116A for observing the subjecteye 12, can suppress dispersion in aberration with respect to lights ofa wide wavelength region including light of the visible light wavelengthregion and light of the near infrared region. Accordingly, the objectivelens 130 relating to the above-described respective embodiments can beapplied an ophthalmic device that is exclusively used for SLO, and theophthalmic device that is exclusively used for SLO can be switched froman ophthalmic device for SLO to use as an ophthalmic device for OCT. Thesixth embodiment is structured such that an ophthalmic device that isexclusively used for SLO can be switched from an ophthalmic device forSLO to an ophthalmic device for OCT.

FIG. 17 illustrates an example of the structure of an ophthalmic device110A relating to the sixth embodiment.

As illustrated in FIG. 17, the ophthalmic device 110A relating to thesixth embodiment has the relay lens device 140 that is exclusively usedfor SLO and that relays the scanning light of the SLO unit, and theobjective lens 130 (refer to FIG. 2 as well), and is formed as a devicethat is exclusively used for SLO. The relay lens device 140 is disposedat a relay unit 140A that can be inserted into and removed from theophthalmic device 110A. Namely, the ophthalmic device 110A functions asa device that is exclusively used for SLO, due to the relay unit 140Abeing mounted to a relay lens mounting portion (not illustrated) of theophthalmic device 110A.

On the other hand, a relay unit 140B can be mounted to the relay lensmounting portion (not illustrated) of the ophthalmic device 110A. Adichroic mirror DM5 that splits and combines light is disposed on theoptical path of the relay lens device 140 at the relay unit 140B.Further, an OCT unit is disposed at the relay unit 140B on the opticalpath that has been split-off by the dichroic mirror DM5. Accordingly, bymounting the relay unit 140B to the relay lens mounting portion (notillustrated) of the ophthalmic device 110A, the ophthalmic device 110Afunctions as a SLO device and can also function as an OCT device.

In this way, in accordance with the sixth embodiment, there is anophthalmic device that can work as both a SLO device and an OCT deviceby replacing the relay lens device 140, which a device that isexclusively used for SLO, with a relay lens 141 that has the samecomponents as the relay lens device 140 and has the dichroic mirror DM5built therein, and by mounting the OCT unit.

Further, a great decrease in cost is possible by using the objectivelens 130 in common, and using the lens structures of the relay lensdevice 140 and the relay lens 141 in common, and structuring theophthalmic device in which both SLO and OCT are possible from a devicethat is exclusively used for SLO.

Note that, although the above describes a case in which the relay unitis mounted to the relay lens mounting portion (not illustrated), theremay be a structure in which the relay lens device 140 is formed byplural lens groups, and the relay lens device 140 is fixed to theophthalmic device 110A, and the dichroic mirror DM5 is inserted into andremoved from the space between adjacent lens groups. In this case, thecosts can be further decreased because switching of the relay lensdevice 140 is unnecessary.

In this way, because the technique of the present disclosure includesthe function of structuring an ophthalmic device at which both SLO andOCT are possible from an ophthalmic device that functions as a deviceused exclusively for SLO, the technique of the present disclosureincludes the following first technique.

(First Technique)

An ophthalmic device having:

a first optical path having a scanning section for angle-scanning alight bundle that is from a first light source;

an objective lens guiding the light bundle scanned by the scanningsection to an subject eye; and

a relay lens disposed between the scanning section and the objectivelens, and guiding the scanning light bundle that is from the scanningsection to the objective lens,

wherein the relay lens has two lens groups, and includes an opticalelement for optical path combining/splitting that can be inserted andremoved from between the two lens group, and a second optical path,which guides a light bundle, which is from a second light sourcedifferent from the first light source, to the objective lens, isstructured on a reflection optical path of the optical element foroptical path combining/splitting in a state in which the optical elementfor optical path combining/splitting is disposed on the optical path.

Note that the dichroic mirror D5 is an example of the optical elementfor optical path combining/splitting of the above-described firsttechnique.

Further, because the optical system of the first technique includes anaberration correcting technique, following supplemental technique 1 andsupplemental technique 2 are included.

(Supplemental Technique 1 of First Technique)

The ophthalmic device of the first technique, wherein, in a firstcombined optical system that includes the relay lens and the objectivelens, first aberration correction is carried out on the light bundlefrom the first light source, and, at a second combined optical systemthat includes the objective lens and the lens group that is at theobjective lens side among the two lens groups that structure the relaylens, second aberration correction that is different than the firstaberration correction is carried out on the light bundle from the secondlight source.

(Supplemental Technique 2 of First Technique)

The ophthalmic device of the first technique, wherein the objective lensis a lens component that shared by the relay lens of the first opticalpath and the relay lens of the second optical path, and at whichaberration correction is carried out on the light bundle from the firstlight source and the light bundle from the second light source.

Seventh Embodiment

A seventh embodiment is described next. Because the structure of theseventh embodiment is substantially similar to the above-describedembodiments, the same portions are denoted by the same referencenumerals, and description thereof is omitted.

In the technique of the present disclosure, the ophthalmic deviceincludes at least one structure among respective optical systems thatare an optical system for SLO that uses light mainly of a wavelength inthe visible region, an optical system for OCT that uses light mainly ofa wavelength in the near infrared region, and an alignment opticalsystem that is used in alignment of the subject eye. Note that thealignment optical system includes a fixation target projecting opticalsystem and an subject eye position imaging optical system. At theserespective optical systems, there are cases in which the aberrationcorrection with respect to the lens system is different at the SLOoptical system and the OCT optical system. Thus, the seventh embodimentdescribes structural examples of ophthalmic devices that take aberrationcorrection at the objective lens into consideration.

First Structural Example

An ophthalmic device that serves as a first structural example is anophthalmic device for SLO that has an objective lens at which chromaticaberration correction in at least the visible region is carried out. Anoptical system, which includes an objective lens at which this chromaticaberration correction in the visible region is carried out, isdescribed.

FIG. 18 illustrates an example of the structure of an imaging opticalsystem 116B in an ophthalmic device relating to the first structuralexample.

As illustrated in FIG. 18, the ophthalmic device relating to the firststructural example functions as a device used exclusively for SLO.Specifically, the imaging optical system 116B has, in order from thesubject eye 12 side, an objective lens 1130 at which chromaticaberration correction in the visible region is carried out, thehorizontal scanning section (also indicated as H scanner in FIG. 18)142, the relay lens device 140, and the vertical scanning section (alsoindicated as V scanner in FIG. 18) 120 such as a polygon mirror or thelike.

The horizontal scanning section 142 is an optical scanner that scans, inthe horizontal direction, the SLO laser light that is incident via therelay lens device 140. The vertical scanning section 120 is an opticalscanner that scans, in the vertical direction, the laser light that isincident from the SLO unit 18. In the present embodiment, a galvanomirror is used as an example of the horizontal scanning section 142, andfurther, a polygon mirror is used as an example of the vertical scanningsection 120.

The relay lens device 140 has the two lens groups 144, 146 that havepositive power. The relay lens device 140 is structured by the two lensgroups 144, 146 such that the position of the vertical scanning section120 and the position of the horizontal scanning section 142 areconjugate. More specifically, the relay lens device 140 is structuredsuch that the central positions of the angular scanning of the bothscanning sections are conjugate. Further, the relay lens device 140 isstructured so as to include a position that is conjugate with the fundusof the subject eye 12. Moreover, the relay lens device 140 is structuredsuch that the position of the vertical scanning section 120 and theposition of the horizontal scanning section 142 are conjugate with thepupil of the subject eye 12.

The light that exits from the SLO unit 18 is two-dimensionally scannedby the vertical scanning section 120 and the horizontal scanning section142 that structure the SLO optical system. The SLO laser light that isscanned two-dimensionally is made incident on the subject eye 12 via theobjective lens 1130. The SLO laser light that is reflected by thesubject eye 12 goes through the objective lens 1130, the horizontalscanning section 142, the relay lens device 140 and the verticalscanning section 120, and is made incident on the SLO unit 18.

The objective lens 1130 has, in order from the horizontal scanningsection 142 side, the first lens group G1 and the second lens group G2.At least the second lens group G2 is a positive lens group havingpositive power overall. In the present embodiment, the first lens groupG1 also is a positive lens group having positive power overall. Each ofthe first lens group G1 and the second lens group G2 has at least onepositive lens. In a case in which each of the first lens group G1 andthe second lens group G2 has plural lenses, the first lens group G1 andthe second lens group G2 may include a negative lens, provided that eachof the first lens group G1 and the second lens group G2 has positivepower overall. The objective lens 1130 is structured to include aposition that is conjugate with the fundus of the subject eye 12.

Due to the above-described structure, an ophthalmic device that isexclusively used for SLO can be provided.

Second Structural Example

At the ophthalmic device that serves as a second structural example,chromatic aberration correction in at least the visible region for SLOis carried out at the objective lens. An optical system, which includesan objective lens at which this chromatic aberration correction in thevisible region is carried out, is described.

FIG. 19 illustrates an example of the structure of an imaging opticalsystem 116C in the ophthalmic device relating to the second structuralexample.

As illustrated in FIG. 19, the ophthalmic device relating to the secondstructural example has functions of being able to work for both SLO andOCT. Further, the ophthalmic device relating to the second structuralexample includes an alignment optical system. Specifically, the opticalsystem that functions as SLO is used as the reference, and the imagingoptical system 116C includes, in order from the subject eye 12 side, theobjective lens 1130 at which chromatic aberration correction in thevisible region is carried out, the horizontal scanning section (Hscanner) 142, the relay lens device 140 for SLO, and the verticalscanning section (V scanner) 120 such as a polygon mirror or the like.

As described above, because the wavelengths of the lights that are usedare different in an optical system for SLO and an optical system forOCT, it is preferable to adjust the lens structures to as to accord withthem respectively. In the second structural example, because the opticalsystem for SLO and the optical system for OCT are used at the sharedobjective lens 1130, the difference in aberration correction is absorbedat the relay lens device. Specifically, the relay lens device isstructured by two lens groups, and the front lens group (e.g., the lensgroup 144 that is at the objective lens 1130 side of a relay lens device1140 for SLO) is used in common, and, by making the structure of a lensgroup 1146 at the scanner 142 side be a structure that is different thana lens group 1146A at the OCT side, the system is structured so as toswitch from functioning as a relay lens device for SLO to functioning asa relay lens device for OCT. Further, the scanning section that scansOCT light also is different. Therefore, the second structural examplehas, between the objective lens 1130 and the horizontal scanning section(H scanner) 142, the relay lens device 1140 that has a structure similarto the relay lens device 140 for SLO. The relay lens device 1140 has, inorder from the subject eye 12 side, a front side lens group 1144 and therear side lens group 1146, and has, between the lens groups 1144, 1146,a beam splitter 1148 that reflects the OCT light and the reflected lightfrom the fundus. Specifically, the relay lens device 1140 has the lenses1144, 1146 that have plural positive powers in the same way as the relaylens device 140, and is structured to include a position that isconjugate with the fundus of the subject eye 12. The lens group 1146A,which corresponds to the lens group 1146 at the relay lens device 1140for SLO and at which aberration correction for OCT is carried out, and ascanning section 1142 for OCT are disposed in that order at the oppositeside of the beam splitter 1148, i.e., the side opposite the reflectedlight from the fundus. Namely, this is a structure in which, in OCT, XYscanning is executed independently from SLO. Further, the scanningsection 1142 for OCT is disposed at a position that is conjugate withthe pupil of the subject eye 12.

Further, in order for the imaging optical system 116C to include analignment optical system, the imaging optical system 116C has, betweenthe objective lens 1130 and the relay lens device 1140, the beamsplitter 178 that guides the optical path with respect to an alignmentoptical system 138H. Namely, at the imaging optical system 116C, thebeam splitter 178 is inserted on the optical path of the optical systemthat functions as SLO, and the alignment optical system, which includesa fixation target projecting optical system 138HA, an subject eyeposition imaging optical system 138HB and an illuminating device 138HC,is provided at the opposite side of the beam splitter 178. Further, thebeam splitter 178 is disposed at a position that is conjugate with thepupil of the subject eye 12.

Due to the above-described structure, the objective lens 1130 for SLOcan also be used for OCT.

Third Structural Example

An ophthalmic device that serves as a third structural example is anophthalmic device used exclusively for OCT that uses, as the objectivelens for OCT, an objective lens at which chromatic aberration correctionin at least the visible region is carried out for SLO.

FIG. 20 illustrates an example of the structure of an imaging opticalsystem 116D in the ophthalmic device relating to the third structuralexample.

As illustrated in FIG. 20, the ophthalmic device relating to the thirdstructural example functions as a device exclusively used for OCT.Specifically, the imaging optical system 116D has, in order from thesubject eye 12 side, the objective lens 1130 at which chromaticaberration correction in the visible region is carried out, the relaylens device 1140 that includes the beam splitter 1148, the lens group1146A at which aberration correction is carried out for OCT and that isat the opposite side of the beam splitter 1148, and the scanning section1142 for OCT. The imaging optical system 116D has fundus camera opticalsystem Fundus at the transmission side of the relay lens device 1140.The fundus camera optical system Fundus is disposed at a position thatis conjugate with the pupil of the subject eye 12.

Due to the above-described structure, an ophthalmic device that is usedexclusively for OCT can be provided by using the objective lens 1130 forSLO.

Fourth Structural Example

An ophthalmic device that serves as a fourth structural example is anophthalmic device for SLO that has the objective lens 130 relating tothe first embodiment, i.e., the objective lens 130 at which chromaticaberration correction in the visible region and the near infrared regionis carried out.

FIG. 21 illustrates an example of the structure of an imaging opticalsystem 116E in the ophthalmic device relating to the fourth structuralexample.

As illustrated in FIG. 21, the ophthalmic device relating to the fourthstructural example functions as a device exclusively used for SLO.Specifically, the imaging optical system 116E has, in order from thesubject eye 12 side, the objective lens 130 relating to the firstembodiment, i.e., the objective lens 130 at which chromatic aberrationcorrection in the visible region and the near infrared region is carriedout, the horizontal scanning section 142, the relay lens device 140 andthe vertical scanning section 120.

As explained in FIG. 3, the objective lens 130 has, in order from thehorizontal scanning section 142 side, the first lens group G1 and thesecond lens group G2, and has the third lens group G3 between the firstlens group G1 and the second lens group G2. The objective lens 130 isstructured so as to include a position that is conjugate with the pupilof the subject eye 12 within the third lens group G3, and further, isstructured so as to include a position that is conjugate with the fundusof the subject eye. Note that, in FIG. 21, the three lens groups withinthe objective lens 130 are illustrated simply as G1, G2, G3. Thesecorrespond to the three lens groups 134, 132, 133 illustrated in FIG. 3.The same holds in the drawings hereinafter.

In this way, by using the objective lens 130 that incorporates anintermediate pupil therein, chromatic aberration correction in thevisible region and the near infrared region is carried out, and themaximum aperture of the objective lens 130 is reduced, and an increasein the weight of the objective lens 130 is suppressed. Due thereto,there can be provided an ophthalmic device used exclusively for SLO inwhich the weight of the device overall can be lightened.

Fifth Structural Example

An ophthalmic device that serves as a fifth structural example is anophthalmic device having SLO and OCT, and having the objective lens 130at which chromatic aberration correction in the visible region and thenear infrared region is carried out.

FIG. 22 illustrates an example of the structure of an imaging opticalsystem 116F in the ophthalmic device relating to the fifth structuralexample. As illustrated in FIG. 22, the ophthalmic device relating tothe fifth structural example has functions of being able to work forboth SLO and OCT. In the fifth structural example that is illustrated inFIG. 22, the point that the objective lens 1130 of the second structuralexample illustrated in FIG. 19 is replaced with the objective lens 130,at which chromatic aberration correction in the visible region and thenear infrared region is carried out, is different.

Due to the above-described structure, an objective lens for SLO and anobjective lens for OCT can be used in common.

Sixth Structural Example

An ophthalmic device that serves as a sixth structural example is anophthalmic device used exclusively for OCT that uses, as the objectivelens for OCT, the objective lens 130 at which chromatic aberrationcorrection in the visible region and the near infrared region is carriedout.

FIG. 23 illustrates an example of the structure of an imaging opticalsystem 116G in the ophthalmic device relating to the sixth structuralexample.

As illustrated in FIG. 23, the ophthalmic device relating to the sixthstructural example functions as a device used exclusively for OCT. Inthe sixth structural example illustrated in FIG. 23, the point that theobjective lens 1130 of the third structural example illustrated in FIG.20 is replaced with the objective lens 130 at which chromatic aberrationcorrection in the visible region and the near infrared region is carriedout, differs. In this structure, as explained in FIG. 3, at theobjective lens 130, aberration correction for both the SLO opticalsystem and the OCT optical system is carried out by the aberrationcorrecting ability of the third lens group 133 (G3) that serves as anintermediate group, and therefore, the structures of the relay lensescan be made to be exactly the same structures.

Due to the above-described structure, an ophthalmic device, which isexclusively used for OCT and in which chromatic aberration correction iscarried out from the visible region to the near infrared region, can beprovided.

Seventh Structural Example

An ophthalmic device that serves as a seventh structural example is anophthalmic device that functions as both SLO and OCT, and uses theobjective lens 130 at which chromatic aberration correction in thevisible region and the near infrared region is carried out.

FIG. 24 illustrates an example of the structure of an imaging opticalsystem 116H in the ophthalmic device relating to the seventh structuralexample.

As illustrated in FIG. 24, the ophthalmic device relating to the seventhstructural example functions as a SLO device and an OCT device.Specifically, the imaging optical system 116H has, in order from thesubject eye 12 side, the objective lens 130 at which chromaticaberration correction from the visible region to the near infraredregion is carried out and that includes the first lens group G1 throughthe third lens group G3, and has the horizontal scanning section 142,the relay lens device 140 and the vertical scanning section 120, andstructures an optical system for SLO.

In order to absorb the difference in aberration correction that is dueto the difference in the scanning lights of SLO and OCT, in the seventhstructural example, the optical system for SLO is used as the reference,and the system is structured so as to also accord with an optical systemfor OCT by adjusting the structure of the first lens group G1 of theobjective lens 130 (refer to FIG. 16 as well). Namely, the system isstructured so as to propagate substantially parallel light between thefirst lens group G1 and the third lens group G3, and thesplitting/combining element (e.g., a dichroic mirror) DM1 is disposed onthe optical path thereof. A lens group 134A, which corresponds to thefirst lens group G1 of the objective lens that functions as SLO and atwhich aberration correction is carried out for OCT, and a scanningsection 1142A for OCT, are disposed in that order at the opposite sideof the splitting/combining element DM1. Namely, this is a structure inwhich, in OCT, XY scanning is executed independently of SLO. Further,the scanning section 1142A for OCT is disposed at a position that isconjugate with the pupil of the subject eye 12. By structuring thesystem in this way, the two optical systems for SLO and OCT can becombined, while taking the aberrations of the individual optical systemsinto consideration.

Further, the ophthalmic device of the seventh structural example has thealignment optical system 138H. Specifically, a prism for optical pathcombining is disposed at either one of the front and rear regions of thepupil conjugate position P3 that is within the third lens group G3. Inthe example illustrated in FIG. 24, a case is illustrated in which theprism for optical path combining is disposed in front of the pupilconjugate position (the region where the splitting/combining element DM1illustrated in FIG. 16 is disposed). By structuring the system in thisway, at least one optical system among the fixation target projectingoptical system 138HA and the subject eye position imaging optical system138HB can be placed appropriately.

Due to the above-described structure, an ophthalmic device thatfunctions respectively as SLO and OCT at which aberration correction iscarried out appropriately can be provided, and an ophthalmic devicehaving the alignment optical system 138H can be provided.

In this way, because the technique relating to the seventh embodimentincludes the providing of an ophthalmic device including at least one ofSLO, OCT and alignment optical systems, this technique includes thefollowing second technique.

(Second Technique)

An ophthalmic device having:

a first scanning section for scanning a light bundle that is from afirst light source;

an afocal objective lens system that guides the light bundle scanned bythe first scanning section to an subject eye;

a first optical path disposed between the first scanning section and theobjective lens, and having a first afocal relay system that guides thelight bundle scanned from the first scanning section to the objectivelens;

a second scanning section for scanning a light bundle that is from asecond light source that is different than the first light source; and

a second optical path having a second afocal relay system for passingthe light bundle, which was scanned by the second scanning section,through the afocal objective lens system and guiding the light bundle tothe subject eye,

wherein the first afocal relay system and the second afocal relay systemhave a shared beam splitter, and the first optical path and the secondoptical path are combined by the shared beam splitter.

Further, the technique of the present disclosure includes the followingthird technique.

(Third Technique)

The ophthalmic device of the second technique, wherein

the first afocal relay system and the second afocal relay system havetwo positive lens groups respectively, and the shared beam splitter isdisposed between the two positive lens groups, and

the positive lens group, which is at the shared afocal objective lenssystem side of the first afocal relay system, is structured so as to beused in common as the positive lens group that is at the shared afocalobjective lens system side of the second afocal relay system.

By the way, as described above, cases of using an objective lens incommon for SLO and OCT respectively, and cases in which aberrationcorrection is carried out for only either one light source of SLO andOCT and it is considered that the aberration correction of the other isinsufficient, are included. Therefore, the technique of the presentdisclosure includes the following fourth technique.

(Fourth Technique)

The ophthalmic device of the second technique, wherein

the positive lens group at the first scanner side of the first afocalrelay system is different than the positive lens group at the secondscanner side of the second afocal relay system,

at the first optical path, at a combined system of the first afocalrelay system and the shared objective lens system, aberration correctionis carried out on the light bundle from the first light source,

at the second optical path, at a combined system of the second afocalrelay system and the shared objective lens system, aberration correctionis carried out on the light bundle from the second light source.

Further, because the technique of the present disclosure includes a casein which aberration correction is complete at the shared objective lenssystem, the following fifth technique is included.

(Fifth Technique)

The ophthalmic device of the second technique, wherein

at the shared objective lens system, aberration correction is carriedout on the light bundle from the first light source and on the lightbundle from the second light source,

the positive lens group at the first scanner side of the first afocalrelay system is the same as the positive lens group at the secondscanner side of the second afocal relay system,

at the first optical path, at a combined system of the first afocalrelay system and the shared objective lens system, aberration correctionis carried out on the light bundle from the first light source, and

at the second optical path, in combining the second afocal relay systemand the shared objective lens system, aberration correction is carriedout on the light bundle from the second light source.

Further, because the technique of the present disclosure includes a casein which the shared objective lens system is an objective lens in whicha pupil is incorporated, the following sixth technique is included.

(Sixth Technique)

The ophthalmic device of the second technique, wherein the sharedobjective lens system has:

a positive first lens group G1 at the scanner side;

a positive second lens group G2 at the subject eye side; and

a third lens group G3 that is disposed between the both groups andincludes a diverging surface.

Further, the technique of the present disclosure includes the followingseventh technique.

(Seventh Technique)

The ophthalmic device of the second technique, wherein, at the sharedobjective lens system, a conjugate position (intermediate pupilposition) that is conjugate with the scanning center of the scanner isformed between the first lens group G1 and the second lens group G2, andthe third lens group G3 includes this intermediate pupil position.

Further, the technique of the present disclosure includes the followingeighth technique.

(Eighth Technique)

An ophthalmic device having:

a first scanner for scanning a light bundle that is from a first lightsource;

an afocal objective lens system that guides the light bundle scanned bythe first scanning section to an subject eye;

a first optical system disposed between the first scanning section andthe afocal objective lens, and having a first afocal relay system thatguides the light bundle scanned from the first scanning section to theafocal objective lens;

a second scanning section for scanning a light bundle that is from asecond light source that is different than the first light source; and

a second optical system having a second afocal relay system for passingthe light bundle, which was scanned by the second scanning section,through the afocal objective lens system and guiding the light bundle tothe subject eye,

wherein the second afocal relay system has a beam splitter, and isstructured so as to be able to be switched with the first afocal relaysystem, and, by switching the first afocal relay system to the secondafocal relay system, the first optical system and the second opticalsystem are combined via the beam splitter, and subject eye observationby the first light source and subject eye observation by the secondlight source become possible.

Further, the technique of the present disclosure includes the followingninth technique.

(Ninth Technique)

The ophthalmic device of the eighth technique, wherein, at the sharedobjective lens system, aberration correction is carried out on the lightbundle from the first light source and the light bundle from the secondlight source, and the first afocal relay system and the second afocalrelay system are the same.

Further, the technique of the present disclosure includes the followingtenth technique.

(Tenth Technique)

The ophthalmic device of the eighth technique, wherein the sharedobjective lens system has:

a positive first lens group G1 at the scanner side;

a positive second lens group G2 at the subject eye side; and

a third lens group G3 that is disposed between the both groups andincludes a diverging surface.

Although the technique of the present disclosure has been described byusing embodiments, the technical scope of the present disclosure is notlimited to the scope put forth in the above-described embodiments.Various modifications and improvements can be added to theabove-described embodiments within a scope that does not depart from thegist of the invention, and forms to which such modifications andimprovements have been added also are included in the technical scope ofthe present disclosure. Further, all publications, patent applications,and technical standards mentioned in the present specification areincorporated by reference into the present specification to the sameextent as if such individual publication, patent application, ortechnical standard was specifically and individually indicated to beincorporated by reference.

EXPLANATION OF REFERENCE NUMERALS

1. An ophthalmic device for observing a subject eye, the devicecomprising: a light source; a scanning section that scans light from thelight source; and an objective optical system configured to form apupil, which has a conjugate relationship with a pupil of the subjecteye, at the scanning section, wherein the objective optical system has,in order from the scanning section toward the subject eye, a first lensgroup that is positive, a second lens group that is positive, and athird lens group that is disposed between the first lens group and thesecond lens group, and that includes a concave surface configured todiverge light.
 2. The ophthalmic device of claim 1, wherein, theobjective optical system forms an intermediate pupil, which has aconjugate relationship with the pupil of the subject eye, is formedbetween the first lens group and the second lens group, and the thirdlens group is disposed so as to include a position of the intermediatepupil.
 3. The ophthalmic device of claim 2, wherein, when W1 representsa distance between a lens surface, which is furthest from the subjecteye in the first lens group, and a position of the scanning section, W2represents a distance between a lens surface, which is nearest to a sideof the subject eye of the second lens group, and the pupil of thesubject eye, and D represents a distance between a concave surface,which has the most power in the third lens group, and the position ofthe intermediate pupil, the objective optical system satisfies thefollowing conditions:D<W1D<W2.
 4. The ophthalmic device of claim 3, wherein, at the objectiveoptical system, when R represents a radius of curvature of a lenssurface, N represents a refractive index of an incident side of the lenssurface, and N′ represents a refractive index of an exiting side of thelens surface, a Petzval curvature is a value determined by the followingequation:C={(1/N′)−(1/N)}/(−R) and when C1 represents the Petzval curvature of adiverging lens surface that is nearest to a pupil position that has aconjugate relationship with the pupil of the subject eye in the firstlens group of the objective optical system, C2 represents the Petzvalcurvature of a lens surface that is nearest to the subject eye in thesecond lens group, and C3 represents the Petzval curvature of a concavesurface that has the most power in the third lens group, the followingconditional expressions are satisfied:C3<C1C3<C2.
 5. The ophthalmic device of claim 1, wherein, when φ1 representsa maximum effective diameter of lenses included in the first lens group,φ2 represents a maximum effective diameter of lenses included in thesecond lens group, and φ3 represents a maximum effective diameter oflenses included in the third lens group, the following conditionalexpression is satisfied:φ3,φ1<0.7·φ2.
 6. The ophthalmic device of claim 1, wherein an air gapbetween the first lens group and the third lens group, and an air gapbetween the third lens group and the second lens group are, among lensgaps of the objective lens overall, the largest air gap and the nextlargest air gap.
 7. An ophthalmic optical system for observing a subjecteye, the system comprising an objective optical system configured toforms a pupil having a conjugate relationship with a pupil of thesubject eye, wherein the objective optical system has, in order from aside at which the pupil having a conjugate relationship with the pupilof the subject eye is formed, toward the subject eye, a first lens groupthat is positive, a second lens group that is positive, and a third lensgroup that includes a concave surface configured to diverge light andthat is disposed between the first lens group and the second lens group.8. The ophthalmic optical system of claim 7, wherein, at the objectiveoptical system, an intermediate pupil, which has a conjugaterelationship with the pupil of the subject eye, is formed between thefirst lens group and the second lens group, and the third lens group isdisposed so as to include a position of the intermediate pupil.
 9. Theophthalmic optical system of claim 8, wherein, when W1 represents adistance between a lens surface, which is furthest from the subject eyein the first lens group, and a pupil position having a conjugaterelationship with the pupil of the subject eye, W2 represents a distancebetween a lens surface, which is nearest to the subject eye side of thesecond lens group, and the pupil of the subject eye, and D represents adistance between a concave surface, which has the strongest divergingpower among concave lenses in the third lens group, and the position ofthe intermediate pupil, the objective optical system satisfies thefollowing conditions:D<W1D<W2.
 10. The ophthalmic optical system of claim 9, wherein, at theobjective optical system, when R represents a radius of curvature of alens surface, N represents a refractive index of an incident side of thelens surface, and N′ represents a refractive index of an exiting side ofthe lens surface, a Petzval curvature is a value determined by thefollowing equation:C={(1/N)−(1/N)}/(−R) and when C1 represents the Petzval curvature of adiverging lens surface that is nearest to a pupil position that has aconjugate relationship with the pupil of the subject eye in the firstlens group of the objective optical system, C2 represents the Petzvalcurvature of a lens surface that is nearest to the subject eye in thesecond lens group, and C3 represents the Petzval curvature of a concavesurface that has the most power in the third lens group, the followingconditional expressions are satisfied:C3<C1C3<C2.
 11. The ophthalmic optical system of claim 7, wherein, when φ1represents a maximum effective diameter of lenses included in the firstlens group, φ2 represents a maximum effective diameter of lensesincluded in the second lens group, and φ3 represents a maximum effectivediameter of lenses included in the third lens group, the followingconditional expression is satisfied:φ3,φ1<0.7·φ2.
 12. The ophthalmic optical system of claim 7, wherein agap between the first lens group and the third lens group, and an airgap between the third lens group and the second lens group are, amonglens gaps of the objective lens overall, the largest air gap and thenext largest air gap.